Problem is this... First off, the car is idling a little rough. But the real problem is after the car warms up it's stuttering really bad. Before it would hesitate in a sense to where I would be say 40 miles an hour in 3rd gear cruising and accelerate 30% throttle or so and it would take it a second or two for it to react and then it would lunge forward. Now it's having a hard time running at all when it's warmed up, it acts as if it wants to die. When this happens and I try to rev it, it takes a second to respond and sometimes it doesn't respond to more throttle and clears up on its own within a few seconds. Plugs and wires are fairly new, coil has less than 10k on it, fuel filter just replaced. It's only doing it once it goes into closed loop it seems. I am thinking opti, but don't want to jump in and change a 300 PITA part if I don't have to.

Someone suggested EGR, is there a way to check the EGR to see if it's bad? Also would a bad o2 be causing this as well?

There is no SES light on...

Suggestions, thanks.

 

Anyone?

 

The EGR can sometimes be tested by removing and plugging the vac line to it. However if it's sticking and never closes fully this probably wont help you. I suggest you remove it and clean it real well. Once you have it out, you can compress the diaphragm with your fingers and see if it feels rough when it moves. If it moves roughly, replace it.

I also suggest you clean the IAC and do the other routine items that you may have put off for a while.

If these 2 things don't help you, have a compitant garage scan it to see how the sensors are working. One than can be a pain is the TPS. This is easily tested with a volt meter.

O2's should be changed about every 50 or 60 thousand miles. But I doubt they are your problem.

By the way FYI Vandivere sells the GM vented opti for $198.00.

Good luck