Hello all, I have a 1994 chevy 5.7L 4x4. First thing in the morning the truck will barely run and even backfires when going down the road; idles real rough. Towards the end of the day it will do the same thing but not as bad sometimes it will run like nothing is wrong. Help please!

 

usually an exhaust leak will make it backfire, as for the rough running if the exhaust doesnt solve it, try a tune-up if you havent done one lately

 

It had a Header leak, fixed that today and also put plugs, Distributor cap, and rotor but it still run's like crap.

 

well, i have 2 more thoughts if the check engine light isnt on, EGR valve, or head gasket take a compression test to find out if it is a head gasket

 

Check the vacuum hose running from the TBI to the MAP sensor and replace it if ANY of it comes off in your hands.

 

Replaced the EGR Valve today, fixed the problem. Thanks for everyone's help.

 

awesome

 

Yea I can see this. The pintle on the EGR was stuck between open and shut. At idle it would run rough because it was open. And at mid throttle it would sound like it backfiring when it was actually detonating because the vacuum on the EGR draw isnt open wide enough.