I had an '88 Silverado with running issues. After MANY part replacements, I figured out the composite (plastic) fuel tank baffle had disintegrated and was plugging the entire fuel system. It would idle, but not pull much of a load. Good luck.

 

I just went through this and fixed it today. I did a fuel pressure test and it wasn't reading any pressure at all but it would start the truck. It would run real rough and die out when I tried to drive it. I put EGR valve, dist. cap plugs, wires, sensors, fuel injectors and nothing worked. After the pressure test I decided to pull the fuel pump out and guess what it turned out to be rotted fuel lines on the sending unit letting air into the system. I replaced the sending unit for sixty bucks and replaced the fuel pump while I had the fuel tank out for another forty bucks and it now runs like a top. Good luck. I suggest running a fuel pressure test and go from there. Auto Zone will lend you a fuel pressure tester.

 

I just fixed the same problem in my truck and it turned out to be rotted fuel lines that come out of the sending unit on top of the fuel tank. I replaced the sending unit for $60.00 and replaced the electric fuel pump as long as I was already there for another $40.00 and it runs great. Good Luck. I suggest running a pressure test on your fuel system and go from there. The lines on my truck were letting air into the system so it was running too lean.

 

I had this problem with my 94 pickup and I did all that ya'll said and it ended up being the 8 star looking thing (the pickup) in the distributer, it was cracked and you could not see the crack until it got to operating temps. You can replace the piece on the distributor or you can replace the entire distributer it is up to you. This should work it did for me.

 

If you dont know what the hell you are doing or how anything works quit wasting your time and money on parts and take it do a good honest mechanic, that is how he makes his living. It's pathetic every time here someone say well i put a knock sensor on and i "seems" to run better or it needed it anyway, no it doesn's and no it didn't,

 

I have a 95 Chevy 350 tbi and I'm kinda having the same problems except mine only does it when the motor has sat over night when you try to start it its backfires really bad and if I sit there long enough and hold acceleration while it backfires and acts like its flooding out it clears up and runs like a new truck I have changed just about everything on the motor But it only started this after I put a brand new distributer on it is when all this started and I'm at the end of my patience with it

Idle air
Coil
Ignition mod.
Throttle position
Rebuilt the throttle body
Temp sending units both of them even the pig tails to them units.
Egr valve
Changed fuel pump and filter
Both injectors
Changed ECM
Plugs and wires the whole none yard and still can't figure out what's goin on can anyone explain that or maybe I'm missin somethin? Anything would help out...

 

engine has a miss after warming up smooths out and then comes back replaced cap and rotor button seem to help but still runs bad

 

Here are the rules for a 5.7 I have had many 5.7 trucks in my life.
Throwing parts at it will not fix it. I have found out over time a simple list will save you a ton of money.

1st - Compression test
2nd - fuel pressure test
3rd - Take off and clean the throttle body - While throttle body is off use a small dentist mirror and flashlight to check which type of fuel injectors you have - Are they the old style ( just a hose running to the port or can you see the injector above the port?)

99% of the time when you start having misfires and the truck is throwing codes it's the old style injectors.

4th - take off the cap and turn the crank to test for timing chain slack.

5th if you are new to the truck and don't know the history -
New cap wires plugs PCV and rotor - regardless.

6th Vacuum lines.

7th those cheap plastic hoses. check them the PCV hose is the wrost.

The 1st thing I replace with any 5.7 is ( that is after you check your fuel presser - compression and timing chain test) is to up grade the fuel injection system AND change the intake manifold gasket - if you have the old fuel injection set up most likely you have the bad intake gaskets -

Even if I find the injection has been up graded I still change the intake manifold gasket. If you ever had one fail you know the damage that can occur - Your engine will fill with antifreeze.

It's real tough to figure out a intake gasket problem.
Some things I found over the years that you do infact have a bad intake gasket.

Are you adding coolant like once a month?
Do you ever hear the motor knock when it first starts and then it goes away?
throwing cat codes?
misfires?

Misfire codes on cylinder 3?

Save yourself a ton of money and time
Change the injectors if old and intake gasket.

99% of the time it will resolve all the issues you are experiencing!!!

Lastly Suburbans with rear heat issues or no heat at all.
99% of these no heat problems are cause by a simple "tee" that is often replaced with the wrong tee.

The tee in question is the 5/8 Y tee... most people just buy a tee and replace it - the rear heat needs the proper Y tee with the small hole restrictor built in it - if you have no rear heat no matter how many times you were told to flush it that's what it is.

this is the tee......1998 Chevy Suburban K2500 Auxiliary Heater Hose Connector Tee for V8 5.7L at 1A Auto.com

 

I had the same problem with my 94 chevy that has the 5.7L TBI last year but mine would also cut off,just die.It would start up fast but was missing and than cutting off.I replaced the ignition module (The small module inside the Dist.) and after doing that,the truck has been running really good.
Right now I am having trouble removing a broken starter bolt.That bolt is being very stubborn and will not come out.Looks like it seized to the block wall and will not come out.Tonight after work,I am going to try and drill out the broken stud and than retread and see what happens.
Mando

 

We have a 1994 Chevy Z71. After over $1200 of mechanic work and replacing just about everything. My husband decided to dig deep and discovered a cracked harmonic balancer and loose timing chain was the problem the whole time! Replaced alot of old parts all over only to find out the answer was right under our noses the whole time. Code readers would not tell us these parts were bad. Most people never think to check an old harmonic balancer or timing chain because these parts usually last a long time. If your truck is 20 years old, and isn't running right, check the harmonic balancer and timing chain. We were so happy to find this problem that we wanted to share this info hoping it will help somebody else.