3000gt ATX weirdest problem ever

[drewinator69]

I need help! I'm out of ideas!
Here is the background
purchased 93 3000gt not running due to wiring harness issues from critters
replaced the wiring harness and got the car running. Went to pull it out of the garage and no reverse.
swapped in a transmission that was supposed to be good with only 45k on it. got it out of the garage and drove to town to get new tires. got the new tires and on the way home was cruising at 55 and seemed to loose over drive. then i realized it had dropped to 3rd in failsafe. Got it home and pulled the TCU it looked a bit rough so i picked up a "known good" TCU used and put that in. Took it out for a spin and made it about 1/2 mile then it seemed to go to what acted like neutral. shut it off....waited about 2 mins restarted and got it to move again about 50 feet. Same neutral condition again. shut it down another 2 mins and same deal i an get it to move reverse or drive for about 50 feet or so.
Thought this was super weird maybe another bad TCU? I picked up another one and it does the exact same thing.
I can start the car and within the first min or so of running i can put it in reverse then drive but as soon as i go back to reverse or neutral then drive again its 100% no movement. i can shut the car down again and wait a min or so and restart and same exact thing. this does it for a while but if you run it longer than a few minutes eventually it seems to get too "warmed up" and the shutdown trick doesn't seem to be effective.

I thought maybe the ECU could be bad even though the engine seems to run fine. Could something with the ECU be sending something weird to the TCU causing this weirdness?
Also noticed that if its in P or N and sitting there idling i do get a check engine light but as soon as i put it in D or R that light immediately goes out. I do need to order an analog meter and try to pull that code.

Im just at a total loss of ideas. could the ECU be going out and doing this weird issue with the TCU?
Any thoughts are appreciated!

 

[motomattx]

First off check your transmission fluid and if its full, consider changing the filter, the fluid is checked with the car warmed up and in neutral running.

 

[drewinator69]

Brand new filter and fluid on both transmissions.
Really seems electrical or computer to me. I ohmed out all the solenoids as well and they are all right on specs. How much voltage does the tcu send the pressure solenoid ive not been able to find that info. Im getting about 5v. And how does this trans know when it needs more or less pressure?