[gearheadE30]

Mine is also a '92, and I haven't had any more time to mess with it yet. Drove ~2 hours to Cincinnati last weekend and the tach dropped out on the way there after 30 minutes. It was fine the whole way back, so who knows. Driving ~2.5 hours this weekend, and I'll see if it does it then. I can't really try messing with anything unless it stops working, is the problem. I'll check the connections at the ECM and the cluster, but given that it never, ever happens when the car is cold, it seems like the failure mode doesn't match.