i have an 87 z28 with the l98. was told tps. went and spent 80 dollars on that and the cars still doing the same thing. it runs fine up untill it gets warm. i can hit the gas have throtlle but when i slowly release car starts chugging and running like **** and when i sometimes pull up to lights it dies out. and is a bitch to start. it really gets me cause i was an idiot and test drove it cold and it was great wondeful car start driving it home and it does this and i call the guy and he said i needed to replace that and now wont answer the phone. please help.

 

You need to scan or jumper a & b together on the connector under the steering wheel and see if any codes come up. How long has it been since the car has had a full tune up. Plugs, wires, cap and rotor, pcv, air filter, fuel filter, and O2 sensor. I may have missed something but you get the point. Is the MASS air flow sensor dirty or damaged? I know a tps sensor will go bad, but in all the years I've owned these cars, I have never had to replace one. I can also understand why the previous owner will not answer your calls. Once the car left his place it's really not his responsibilty any more. You never know when something may go wrong with a car. You can test drive it for 3 hours and all is fine. Then when you drive it home and something happens. That does not always mean the the previous owner new that was going to happen. Good luck.

 

Before you start buying parts and replacing what's not bad, try to diagnose it a little bit.
As already suggested, pull the codes to see if there are any.

A common problem on these old injected engines are fuel injectors. You can at least measure their resistance (takes 2 minutes) when cold and when warm. You cannot imagine how many times these caused a hot poor running condition, no-start conditions etc.

Also, if you have access to a datalogging laptop, hook it up and see what is causing yor problem. Sounds very much like a fuel delivery problem, may it be caused by the MAF sensor or the injectors themselves.

Let us know what you find.
Lou