I have a 1994 Lesabre w/ 110k on it, in which I as recently a year and a half ago replaced the ECM. Now, after about 30 minutes of driving, the car starts to surge, even tho it still accellerates quite chopily, and then as soon as I come to a stop it shuts off and won't turn back on till it's cooled off for at least ten minutes. I think it's either my oxygen sensor or my EGR valve. I just hope its not my ECM again. Post any ideas suggestions! Thanks.

Check the coolant temp. sensor, the fan relays, and the o2 sensor. one or a combination of these may be bad. Also, if that isn't the problem, I suggest checking to make sure the Ignition Coils are properly functioning. Does the exhaust look black, and have a bad odor?

You may also have a sticking TCC Solenoid. You may simply unplug it to check.

"You may also have a sticking TCC Solenoid. You may simply unplug it to check."

Ditto.

I had a similar surging problem on my '97 a couple of years ago. Replaced the throttle position sensor and the problem stopped right away.

Always test before replace/purchase.