I have an 1986 camaro and I'm not an expert at auto trans so I'll do my best to explain it. What its doing is when I get up to the 45 mph range and it shifts into over drive (or the TC locks, I'm not sure which), sometimes it doesn't stay there. I don't have a tach so it makes it hard because I have to do it by sound of the engine. Sometimes I will be driving at high speeds like on the freeway and it will be doing fine, then it will start shifting back and forth rapidly and then stay in the lower gear(or maybe with the tc unlocked). The engine runs at alot higher RPM and I don't like to drive it like that because I'm afraid I'm going to over heat the trans fluid.

I had a 93 camaro that was doing the same thing and when I took it in they said it was a sensor that would keep it in a lower gear until the engine was up to temp then it would allow it to shift up. The sensor had been broken off so it was only making contact once in a while which is why it would only work sometimes. Does they 86 camaro have the same sensor, and if it does where would it be? I think the 93's was by the thermostat. Thanks!