Mopar Forums - Torqueflite 727 Sticking

Ok, I know this is a mopar forum and I like mopars but I own and International Scout II which has a lot of mopar parts on it. One of these parts is a Torqueflite 727 tansmission that is giving me a world of trouble right now. I have asked the cornbinder groups what they know and honestly they dont know what is going on.

Here is the deal the truck is a 4x4 and has a torqueflite 727, it was rebuilt about 3000 miles ago by a mopar dealer. After it was rebuilt the truck sat for about 4 years since them I have been getting it going. About 2 months ago I got it back on the road and everything seemed fine, it shifted through all the gears no problems. About 2 weeks ago the transmission stops shifting out of 2nd gear. It will down shift to 1st and up to 2nd but never up to 3rd. Since then I have pulled the valve body and cleaned it. Once I did that it seemed to work for about 2 days and then it was back to not wanting to shift gears. So I put some Sea Foam Trans Cleaner in the fluid and it seemed to work again for about 10 miles and now it will not shift again. This is a problem for me, in a scout 2nd gear only gets me to about 20 miles per hour.

I have had it suggested that it could be the govenor or valve body. Has anyone heard of this problem before, or know a fix for it? Taking it into a trans shop is a little out of my budget right now so anyone that knows about this transmission and can point me in the right direction I would appriciate it