I posted a lengthy description previously but after some more troubleshooting this is the shorter version. I have pressure gauges connected to the pump and torque converter (TC) test points with hoses so I can watch them. Several people suggested I had problems with inching valve so I removed the brake line from the inching valve and capped it - opened inching valve and spool seems to be moving freely - left the brake line disconnected so nothing can actuate the inching valve.

When first started I have to rev the engine a lot to get it to move in both forward and reverse. Pump pressure 60 to 70 psi at idle - up to 190 psi at full throttle. Torque converter (TC) zero at all engine speeds.

As it warms up the truck shifts into gear more crisply and moves better with less throttle but still slipping some - wont spin the tires if I push against something with the forks. TC still zero pressure.

When it is moving pretty good I take it on the driveway and get it moving quickly at full throttle - TC pressure starts to climb to 40 psi as truck gets to full speed. As soon as TC pressure starts to climb the pump pressure jumps up and stays at 150 psi minimum even when I let it idle. No slippage - it will spin the tires if I push the forks against something solid.

Summary - pump pressure stays low at idle like flow is going back to sump and TC pressure zero. Once it warms up and TC pressure starts to climb when driving pump pressure goes to 150 psi minimum at all engine speeds like the pressure regulator valve starts working but TC pressure still zero at idle.

I think I have eliminated the inching valve by disconnecting it but not sure what to try next ???