I have an 88 Trans am what has a bad miss when it is idling, it will also idle rough when it is in its warm up cycle but when it finally come out of the warm up cycle it runs better but there still is a miss, during the warm up cycle there also is a a bog when you first give it some gas.

We just finished a partial rebuild on the engine, i had to do a valve job. When we rebuilt the top end we put in new spark plugs, new wires, rewired the electric fans and took off the air pump for the smog. After the car was finished it ran fine for a few weeks until easter when it started missing and lost all power.

Since then we have replaced the igination coil, new spark plugs, checked the plug wires we also resistanced tested the tps and there were no spikes or drop offs, we resistanced tested the injectors hot and cold and they were all around 16.1.

I got a check engine light yester day and it was a code 15, i cant remeber the first part but i know the second part had to do with the ECU, we also have a distributor in it from an old chevy truck that was use as a replacment for my broken accel distributor.

What im wondering is should i replace the distributor or the ECU or is there somthing else i should look into first?

Code 15 is your coolant sensor. Have you cleaned the passages inside of your throttle body, more specifically the passage and pintle of the IAC motor? Even the smallest amount of buildup will effect idle quality.