I have a 1994 z28 with about 140000 miles on it. It will run fine will it is cool as soon as it heats up. It will start missing and lose power. I have changed spark plugs cooling temp sensor fuel pump. I unhooked the cat and when it heats up it smokes and smells really bad. then will start glowning. i took it to the shop and they told me it was bad. thats the only thing that could be left.

any one know anything else that it could be?

 

Clog Cat converter? OPTI?

 

Rather than guess, you should have it scanned. Does the SES light on the dash board light up?

Your description that the misfire happens when the engine warms up might point to systems that take over managing the engine when it transitions from "open loop" (cold) to "closed loop" (hot). These include a variety of sensors. Mass Air Flow, and Oxygen sensors are the first that come to mind.

Throwing parts and labor at the problem is expensive. Get the PCM scanned as a first step.

 

Well, a glowing cat is a really good clue as to what's going on. Scanning for codes on a 94 won't give that one up.

Please explain what you did again. Was the cat 'glowing' and then you took it off? If that's what you did, does the car run better with the cat off?

 

Thanks for all the info.. Got it fix the cat and plugs where bad