1991 Nissan 300ZX automatic transmission problem


I have a 1991 Nissan 300ZX 2+2 with just over 100K miles on it. A few years ago, the automatic transmission began to drop out of overdrive at about 60 mph and wouldn’t kick back in unless I got up to 70 mph or so.

I’ve had multiple auto shops work on this. At the suggestion of the first one, I had the transmission rebuilt. Not only did this not correct the problem, the car would now (sometimes) not shift into overdrive at 40 mph.

The last time I got it back from the 2nd garage (after many attempts to locate the problem), the A/C wasn’t working properly.

The latest mechanic hasn’t been able to isolate and correct the transmission problem either even after consulting with people he knows at Nissan. (No one seems to be able to fix the A/C problem either.)

I live in the Johns Creek, GA area. I’d like to keep this beautiful car but can’t keep putting money into it. Does anyone have an idea of what the problem(s) might be and/or know a good mechanic or auto shop in this area?

Thanks so much!