Last week i bought my second 91 camaro 305 tbi. Car ran like a dream had no issues. Friday i left in it to run a few errands and the idle at the stop light started to go down really low then back up. Then it just died on me i was able to restart it and keep it running at lights by holding down the gas pedal a little while stopped. While im driving it runs fine doesn't cut out or anything its only when im stopped at idle. I cant figure this out fuel pump is working fine. Anyone else have issues like thia

 

Ok my ecm is throwing codes 15 21 and 23 coolant temp sensor has been replaced and that was the one that said the most about idleing issues