I read thru most of this. It doesnt sound like you have checked line pressure.
Also the plug for the shift pack can also leak. Pull the shift pack plug and get a mirror and see if there is any atf inside that plug. If so clean it our with contact cleaner and get some die electric grease and pack inside and put back together.

I've been limiting the amount I drive the truck to about one trip a week in hopes of at least making it to the rebuild. Today I drove the truck for over an hour up and down the highway up to 70 mph and down to 45 and nothing happened, so I'm guessing it has to be heat related since all summer was a headache. Oh and to the previous post I haven't checked the line pressure but the plug for the shift pack is dry and packed with die electric grease. I'm kind of glad to do a new tranny though since its a truck that will be a round a while, and I have permission from my better half to drop $4000 into the truck its hard to turn that down. By the way the $4000 includes some performance upgrades, some Doug thorley tri-y and a bbk throttle body.

So a quick update, so finally found a trustworthy transmission shop. Left it for a day so they can run a few tests on it and the conclusion is transmission is on the verge of breakdown. I've been driving it the past week or so as much as I can since I have most of the money available, and its on its last leg hopefully enough is left to get it to the shop when ready. Thanks for everybody's help on the subject.

Its hard to find a good shop . Check on a Ford reman they have a great warenty