Nissan 1993 240SX stuck in 1st or 3rd - digital display bad

Mileage: 140000 automatic; intermittent problem of shifting. Starts out in 1st gear won't shift to 2nd. Sometimes will "jump" into 2nd, sometimes have to stop, restart. Which sometimes works. This happens about 60% of the time. Also, at a stop light, after it has been shifting fine, it gets stuck in 3rd in starting out and won't shift to 4th. I usually pull the car off the road, turn off, restart which is effective 75% of the time.

The digital display mostly doesn't work, but does come on about 5% of the time. The radio and dashboard lights & tachometer (of course) don't work, , but oil, gas, door open chimes do work. Oh, the radio light came on the other night for 5 seconds. If the digital display (+ heads-up display) does come on, it will stay on till car turned off. Start back up - display is gone.

Automatic transmission, computer, computer sensor - all fine. Replaced sensor, all injectors, spark plugs & wires & more not related. No one (Nissan dealership, transmission shop, electrical shop, import repair shops) can fix this.

Heat / Cold -- not a factor. Please help - I'm at a loss !