2007 Mitsubishi Raider P1745

I have a code P1745 that came on m to truck for awhile, I went through codes and it says line pressure to high. Change my solenoid on the transmission and that didn’t fix the problem. Transmission shop said it didn’t fix problem, went through my transmission by burning it up driving it. I recently just bought another transmission. Code still says the same. Just bought a computer for the truck , was told that if I replaced the computer , I would have to get computer flashed to worked the vehicle.