It's so hard to say. That's a weird one and without being able to actually be there to monitor what and why any ideas would be nothing but guesswork. Have you replaced the solenoid pack pictured above yet?

D

 

Yes I have, the one that I assumed was the o/d solenoid which is what the "mechanically inclined" employee at autozone said it was is actually the tcc solenoid

 

It's almost like the transmission is getting hot and then it slips out of o/d because it only does it after I've driven for 45 minutes or so.. And it doesn't do it all the time. I'm thinking I may try to get the transmission flush. Maybe there's some build up in the coolers.?