This is a ’93 LE 2.2 four cylinder. When it is cold it idles and rev’s up great. As soon as it reaches a working temp the engine starts running rough and it’s almost as if it’s only running on three cylinders. When I stop after driving (and jerking) the engine smells like exhaust gas. Sometimes during the drive it is as if the engine has power surges and tends to run fine for a moment or two.
I have done a fair share of trouble shooting but with no success to finding the problem. The following valves and sensors check out fine. TVV, throttle opener, gas filter, idle up valve and EGR valve. I am not sure how to check and test the other vacuum components.
I have used the vacuum diagram found on this site for reference.
I would appreciate all and any advice.