Pontiac: 93 Grand Am V-6 hesitates on freeway, fuel filter replacement, oil fuel

Question
My local mechanic doesn't know how to diagnose this because the problem goes away once the car cools down.

After freeway driving for about 30 min, the "check engine" light comes on.  Sometimes the light just blinks on and then off a few minutes later.  Other times the engine starts hesitating and lurching like the engine is being starved (gas, air?).  I can keep the engine running if I force the gas but it will continue to lurch (front and back jerking).  When I pull off the freeway, the engine continues to rev high and it seems like the engine is still in a high gear.  I can stop forward movement with the brakes, but the tach stays at 1500+.  If I put the gear in Park, the tach goes over 2000 and revs high.  The last time I did this I managed to get to my repair station and after about 5-10 minutes of this high rev in park the engine overheated and spilled some coolant from the overflow.  Anyways, the main symptoms are: almost always freeway driving starts it; engine jerks/hesitates; engine won't shift down at stop.

Recently the service light has also engaged during street driving.  When this happens the idle drops below 500 at stop and the engine suddenly dies/shuts completely down.  On restart, which takes several attempts and pumping the gas, the engine revs high like it does after the freeway and the engine jerks like before.  The car died suddenly once before on the freeway at about 40 mph.

After first incident, I had an oil change and oil/fuel filter replacement.  No effect.

Could this be a torgue converter issue?  Any ideas would be appreciated.

Jason

Answer
What mechanical work has been performed on the vehicle recently ?. As most problems that occur after a recent repair was made can be traced back to the area of where the repair was made.

Whenever teh CHECK ENGINE light illuminates it stores a CODE(S) in the vehicles computer.

You need to extract the codes and let me know what they are.


Thomas