99 Explorer 4.0 4R44 Trans Help

Hello, I'm working on a 99 Ford Explorer, its a 5th month 4.0 4R44 Transmission. The problem is it has a bad "flash-up" shifting into 3rd. I have run across this a few times and I can never seem to fix it completely. Re-rebulids come out of my pocket... this is a big problem needless to say. Any help to this would not be tak'n for granted.

Your transmission should be a 5R55E. Which is a 5 speed. If your working on units with about a 100K miles. Then pitch the valve body and buy new one. Comes loaded with solenoids. There are also aftermarkert VB recalibration kits.