When cold my truck starts fine and runs great. When it warms up the injectors stop spraying if I let it come down to idle. If I hold it even a little over idle it runs smooth and if I prime it with something as it starts to die it revs and the injectors spray. It is only at idle that I have a problem.

The injectors have a good clean spray pattern when they are working.

I have changed the MAP sensor.

I have changed the IAC.

I have changed the throttle position sensor.

I have rebuilt the throttle body, everything but new injectors.

I have a check engine light for the knock sensor but I am not having ignition problems so I don't think it is the problem, am I wrong?

I assume since it runs good at high RPMs that the fuel pump is good.

It has the 350 tbi...

I am hoping to fix this without going to a mechanic. Even if it takes me longer than I like(which it has already) and if I waste money on parts I didn't need I am using this as a learning experience at this point.

Thanks in advance for any help. If any other information is needed just ask. I'm typing this out on an iPhone and I don't know how to scroll up to see what I missed... lol

 

So what is this dealie with the knock sensor?

It may have the internal fault that tells the computer to turn off the fuel pump. When you spray START GOOD into the throttle body it only stays running because they spray is flammable and you have spark.

 

Well, when I prime it as it starts to die the injectors start to spray again and I haven't had a code pop up since I first started having problems. I have let it sit until it dies and drove down the road being a little hard on it so I think the knock sensor was a one time thing, possibly 4 wheelin a couple months before it started having issues.

 

Common problem. First Guess: You need a new distributor shaft.

Alternatively, you could just replace the distributor with a known-good used or rebuilt unit.

Magnets on the shaft get weak, send no signal at low RPM.

 

If this was the problem wouldn't it have problems getting fire? Even when it won't start I have a good fire.