Just want close up this thread that I started.

I Installed a spin on filter on the return from the cooler to the transmission. Ran the rig for about 100 miles, changed spin on filter and ran for another 250 miles. Symptoms were the same throughout. Great when fluid was cold, and poor when fluid had warmed up. I cut open those filters and the first was packed with junk, the second looked much better.

After those 250 miles, i replaced the spin on filter yet again. I also dropped the pan, flushed fluid, and installed a Broader Performance valve body with a new filter.

So far it has been about 1000 miles with no problems at all and very firm tight shifts. We'll see how long it will lasts, but i'm very happy so far. Thanks everyone for their help!

 

Gary Lewis used a Sea Foam tranny additive to help some crud out. Seemed like it had some alcohol and other tranny fluid compatible solvents in it. That may help as well.