Some Help Please. (transmission - oil pressure)

[New York City]

Ok let me start by saying.
I had my transmission start slipping on me.

I got it rebuilt with a new torque converter.
But before when it was slipping, my oil gauge would jump to 80 and back to the middle when I would accelerate.

I thought it would be fixed once the transmission was rebuilt.
Well it is still the same. When I accelerate the oil gauge on my dash jumps towards 80 and then back to the middle when I stop accelerating.

My questions are:

What may be the problem? (Is it the oil pressure sensor that went bad when I would accelerate my hummer and force the gear to kick in when my tranny was slipping?)

How urgent do I need to change the oil pressure sensor if so? (Damage outcome if I wait?)


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Now my h2 is having slipping issues again. I had a check engine code come on for a solenoid. The tranny place has ordered it and will be installing it as soon as I come in. (the car is driveable, just has a slight slip when going in 3rd gear. Drives good after that) But this is the second time in 1 month the solenoid is going to get replaced. Any clue what is going wrong?

Also, what tranny fluid should have went into the tranny?
(I'm asking to make sure they put the right one)