As a testing procedure you could try unplugging all the sensors and strting it up and letting it warm up that way. It won't run very well but perhaps might isolate the computer from some odd fault that one of them has. Or just try unplugging one sensor at a time - coolant temp, intake air temp, and manifold pressure.

I had a brain box fail on my 71 1800E once - it suddenly started failing to turn on the fuel pump. In retrospect I now realize I could have easily just wired the fuel pump relay so it was on whenever the ignition was on with little if any ill effect, but I found a new box instead.