Rough Idle

[shawnboy]

Tons of power at first but once the engine has run a while the power fades noticably and has a rough idle when in gear and at a stop. 1990 Jimmy, 350. I swapped out the temp sensor and replaced the vaccuum lines. The problem is still there. Any suggestions?
Thanks.

 

[Leper]

Make sure it has plenty of oil and water in it. It sounds like temp is causing you the problems. Electrical components are the most likely cause, if the motor internals are ok. With the engine running, and at normal operating temps, run your hand over each plug wire. If you get a shock, you have a wire grounding out. Replace and see if the problem goes away.