Ok let me try to summarize a long story. When I got my 86 camaro with a 2.8L v6 and a 5 speed manual transmission the ecm was just hanging down in the passenger side floor board and had 85 cavalier written on it in wax pencil. I assumed that they just didn't have the bracket and that's why it was hanging down. The car broke down one time and I thought that it was the ecm so I replaced it with a new one from o reilly's and put the eproms from the one that said cavalier in it. The car never really had much power up to this point but it ran. Well my heater core started leaking so I decided this would be a good time to put it up in the dash like it should be. I then discovered that the original ecm was still in there and that the previous owners must have been lazier than I am.

I tried hooking up the old one and the car wouldn't stay running, so I then put the eproms from it into the new ecm and eureka the car ran better and had more power than ever before. The problem is that now it idles too high until it has been running for a while and even then it still occasionally idles too high. Any ideas on how to fix this?

 

first thing to do is check the IAC and TPS adjustments and see if that helps.
https://www.thirdgen.org/tpimod2