When my 77 z shut off I did what Blue talked about and looked at the ignition module. I got a Nov 77 module (from junkyard, had different connector from my July 77 but the same wires) and all seemed well. I still get an irratic idle every other start. On rev after letting off gas it dips to 500rpm and then moves up to 700-800.(normal?) I recently replaced the plugs with ngk and got a new coil because it was so old. I have replaced all elec connectors. Still irratic. Car didnt start yesterday after warm up so I pulled cold start connector. Started right up. Checked thermo switch and it is working correctly. Left off the cold start this morning and it started fine but still irratic. Went for drive of 10 miles and worked great. Went to start it after sitting 20 minutes and sputtered but started and drove home fine until 1 block from home. Engine shut down tach stayed around 2000 not 0 so it must not be the ignition module. what next???