I have a problem with my 91 s10 4.3 auto. It runs smooth for one second, then idles rough, smooths back out, then rough. It does this the whole time it is running. I had the spark plugs, wires, cap, and rotor, along with the egr valve and iac valve replaced, and it didn't change a thing. What can this problem be?
Forgot to add that while the vehicle is in motion it drives great and doesn't miss, only idles strange, and has a rotten egg smell on top of it.
Forgot to add that while the vehicle is in motion it drives great and doesn't miss, only idles strange, and has a rotten egg smell on top of it.