OG trans 250k gimpy after fluid change

[Mhks68]

Well. Dropped the pan and the screen. Scrubbed both up well. New gaskets. Refilled fluid to cold full on the dipstick. Now,once in gear, reverse or drive, she’ll roll a bit then not move. Like she’s in neutral. The idle will go up. You can rev. No movement. Then it’ll catch and she moves again.
It’s alright once she’s going. KD is adjusted well. Old fluid looked old but no glitter. No shrapnel. Magnets had usual gunk.
Any suggestions. Aside from the manual option.

 

[WILLD420]

Mine does a similar thing. It will also go into neutral in 2nd gear when you first get going after an overnight stay and you go around a corner, lift, then reapply throttle. Converter drainback will fill all the passages in the trans with air. It takes a few minutes of pumping to get everything working again. I just start the truck, throw it in neutral and let it idle for 30-45 seconds. Then hit reverse, it will move a little, then lose drive. I'll throw it in neutral, then hit drive and it will usually go good from that point on until I turn it off overnight. These things are getting old and valve body issues happen. A really good trans shop can probably fix it without a rebuild, but the vast majority of them will just tell you to do a rebuild, take your money and not fix that much.