Well I took on my first transmission and it seems I did okayish.
After getting everything in I topped off all the fluids and ran it through the gears. Shifts seemed fine but neutral still spun the axles. Didn't think much of it as it didn't have any weight to hold back the axles. Got it on the ground and rechecked all the fluids with it level and warm. Now it goes in gear but very weak and will barely move. In neutral I'm creeps forward like in first but if I brake it will Rev without being bogged down. I appreciate the help just trying to get a plan so I hopefully don't have to pull this thing back out.

Well I took on my first transmission and it seems I did okayish. I did the clutches, sprags at the sun gear and a transgo Jr shift kit.
After getting everything in I topped off all the fluids and ran it through the gears. Shifts seemed fine but neutral still spun the axles. Didn't think much of it as it didn't have any weight to hold back the axles. Got it on the ground and rechecked all the fluids with it level and warm. Now it goes in gear but very weak and will barely move. In neutral I'm creeps forward like in first but if I brake it will Rev without being bogged down. I appreciate the help just trying to get a plan so I hopefully don't have to pull this thing back out.

1991 buick century wagon.

Did you air check it completely before sealing it up? Are you full throttle and doesn't move? Do the RPM'* go high but no movement? Help us here.

I air checked 1,2,3 before installing. Higher rpms don't make much of a difference. All the gears seem to be there but they aren't getting enough pressure.

I also added a transgo jr shift kit. I thought I added that to this post but it looks like I accidentally made a new one.

is your modulator setup right and is your TV cable adjusted right

fluid level

I changed out the modulator last night with the old one with no change. The rebuild kit came with a new one that was a little different so I thought I’d give that a shot. TV cable I haven’t made any changes it was working fine before. Seemed like it went back on without any issues. Fluid is good.

Car off, how much slack is there on the tv cable with a gentle pull by the tear drop on the wire
Car running in park idling, same question

you said 91
are you SURE you dont have a 4t60e NOT a 440t4(4t60) ? 91 would most likely be an electronic controlled trans