1994 K1500 4L60E Issues

[Bimmster]

Rebuilt in December 2019 and sat up for a long while. Started to shudder on up shift from first into second under heavy throttle then started to worsen to medium throttle. Parked again ...then a short while ago the aux cooler blew and lost fluid. Son revved it and got it off the road way. Now getting an over rev on up shift into third and some times slipping all under light peddle application. Fluid looks and smell okay and is at or slightly above full when hot mark in park warmed up?
Thoughts ? suggestions? welcome!!

 

[NickTransmissions]

Rebuilt in December 2019 and sat up for a long while. Started to shudder on up shift from first into second under heavy throttle then started to worsen to medium throttle. Parked again ...then a short while ago the aux cooler blew and lost fluid. Son revved it and got it off the road way. Now getting an over rev on up shift into third and some times slipping all under light peddle application. Fluid looks and smell okay and is at or slightly above full when hot mark in park warmed up?
Thoughts ? suggestions? welcome!!

Yank and rebuild it. 3-4 pack is shot, prob forward clutch as well. Pressure test drum and carefully inspect forward piston housing (it may be worn).

Purchase a new torque converter. Replace all soft parts, one way clutches, bushings, accumulator pistons, pump internals and electrical components. Turn rev input drum and remachine pump halves.