Rebuilt my th440/4t60 transmission for my 1990 Oldsmobile cutlass. Now the tranny is very sluggish, barely moves. If I lift front end off groun, all gears work and move the wheels. I put rebuilt torque converter in and fluid is at correct level. Any thoughts/ideas appreciated. Thanks.

Are you sure that it is full of fluid?
Does it move OK in reverse?
Have you ever rebuilt one of these before?

Moves the same in reverse as forward gears. With all four wheels on the ground it barely moves backwards/forwards. When lifting the front wheels off ground it moves in all forward and reverse. I am sure the fluid is at right level. Disconnected cooler out line and ran vehicle for a couple seconds and fluid streamed out line. Never rebuilt one of these. Followed the atsg rebuild manual.

What was the original problem? It sounds like you may have an input clutch or input sprag problem.

check the line pressure w/a gauge to verify that you have the proper pressure.

Are you sure that you have used the correct valve body gaskets and placed them in the proper position?

4th clutches were burned, 3rd roller sprag was torn up, the bearing on center of shaft was destroyed.

I would like to check the line pressure. My atsg rebuild manual is for this year of transmission and the majority of the transmission is the same except for my transmission never had an input clutch accumalator piston in the channel plate. Thought it was missing, but there is no hole in channel plate for a piston to do anything there. (Went to junkyard and looked at other trannies and they all had a hole in the channel plate for the piston.) The two letter code on my transmission is "YD". But the atsg rebuild manual does not list the "yd" transmission. (bought 2 atsg manuals covering 1985-1995 for this reason. The line pressure varies for different transmission codes, so I don't know what the correct pressure should be.

Rule of thumb is 60 PSI idling in Drive and it should more than double on full throttle. But you can just pull the TV cable all the way out to see if you have pressure rise.

Ok thanks! I will check tomorrow.

Tested oil pressure and had 120 psi constant in idle and full throttle in all gears except for 1st gear which jumped to a constant 180 psi.

Sounds like you have an internal problem.