auto tranny guys come in

What kind of fluid are you using? The method I used was to run the engine to operating temp, then park it on a level surface, put in park, go slowly to reverse, then n, then OD,then D, then 1, then back up to P slowly, then back down again, then back up to P. The hard gear engagement sounds like low fluid.. but foaming definately isn't supposed to be happening to the extent that you're noticing it on the dipstick.

You have a tranny cooler on there with that stall right? .. and when was the last time you had it fully flushed, TC and all?