I have a 1999 monte carlo z34, 3800 engine. The car surges every day (even more since it's been cold outside) usually after driving several miles. Sometimes the jerking only lasts a few minutes, other times it's for the entire trip. It will surge uphill and on level roads. The RPM's bounce around like crazy when the surge occurs. There are no codes on my dash. I have searched online for hours, and it seems to be a mystery. All of the surge questions remain unanswered. I have had the car to the shop, but the car didnt act up for the mechanic(Surprise!), so he was unable to diagnose a problem. If anyone has had a similar problem, and was able to find a solution, please respond!

 

Jason........I have a 2000 MC with the same problems along with another friend. The "throttle" switch was replaced in my friends and worked. However this didn't work for me. Good Luck........

 

i have a 95 lumina so not sure if this helps.
(tranny is good here) what i ended up doing was checking the ignition packs. i found the 2ns one was bad replaced that, along with (since i was already into it) wires and plugs.
it runs PERFECT now. but i had the same symptoms u had. out the pack fixed the problem.