okay heres wats up.. i took my car into the shop today 97 pontiac t/a.. because it has been spittering and sputtering BAD.. like at times it wont go over 20 miles per hour and is hard to get going.. but heres the thing it runs totally fine at first when you start it up cold but then after like 15-20 min. of driving its like someone pinches the fuel line or something it starts shaking and cutting out and back firing BAD!!! the guys at the shop noticed that the cat. converter was nearly completely clogged so they gutted it while a new one comes in.. the problem is still there.. and oh yeah my cars temp. keeps climping and declining from starts and stops from 160 to 220 at every stop..
PLEASE HELP!!!!!

 

I don't know how, but it sounds like your ECM is going out. The reason I don't know how, is the "going out" part. Computer hardware works, or it doesn't. There's no in between. When you are sitting on your computer, and it crashes, that's software being corrupted. Our cars software is built into hardware differently than our home computers. From my understanding of our 'software', is it has some that can be changed (the learn block) but it doesn't read and write it to PROM as it would a hard drive.

Now, explanation aside, the not going over 20 and sputtering REALLY bad, sounds like Limp Mode. As for the temp jumping around, that runs off a different sensor I think even for your car. If the gauge runs through the ECM, then that's even more to the theory of it going out. I would check and see if you can remove your chip from your ECM. I assume that, even with your style PROM being reflashable inside the ECM, it's still removable. Doing that will make it go into Limp mode. Compare how it acts then, to how it acts when it can't go over 20.

Sorry I can't be of much help.

 

Sounds to me like its ok in open loop...then when it goes into closed then you have the problem...check for codes set...then replace the O2's...and then maybe the temp sensor.

 

I second this, running good while cold but then not is usually O2s, especially if it still runs good at WOT.