So no one on here knows me, I usually am on the "Pontiac Forum" but the turn out there has dwindled to a all time low so I was looking around for a new site. I run a '98 3.1 (Yeah the 3.1) and have been doing a good bit of work since I got it.

After all the work, the cars idle is at an average 770 at idle with a solid idle. But the problem still comes from after driving around, I will come to a stop and the car's idle will surge every 5-15seconds. It keeps a constant for a few seconds then it has a quick 1-3 second surge and staggering idle until it drops back down. Only necessary systems on when this is happening (no heat, etc.)

I've done the whole coolant flush, oil change, EGR/Throttle Body/MAF/IAC clean, checked every hose for a leak. Replaced EGR/TB gasket, Fuel Filter, Air filter, Thermostat, Plugs, Wires, Ignition Coils & Radiator Cap.

I had the same issue before all these parts were replaced, and while my car is driving much better then before these parts the "While driving idle" seems to be my reoccurring problem. I've also noticed a "surge" in speed while on the highway, such as if my car were in cruise control when it hasn't even been being used. (For example, I've been doing 70 on highway, drop down to 55, even may have used brake, and the car will try to go back up to speed without me doing anything) There's always been a big of hesitation between the moment I apply pressure on the accelerator and the response, less now that I tightened the cable, but still what I would say a recognizable delay in response.

My research keeps going to one item, "Throttle Position Sensor" But I have no check engine light, it's been awhile since I have. Am I mistaken to believe that you should definitely get a Check Engine light if the TPS is either blown or malfunctioning. Some guy at Advance Auto said It would only if broken, not malfunctioning, it said It could last awhile not working right before I get a Check Engine light, is that true? Does TPS sound like a reasonable solution. My OHM is broke and I don't want to get another because I never used it to begin with.

So if anyone had this problem and fixed it, or has a reason to believe they know what should be done, lets figure this thing out.