Check around for the mt-82 threads.... there are many fixes for this issue. It is fairly common, but not so much at as low of RPM's as you are mentioning.... Mine used to stick 1/4 of the way down at 6800+ RPM's.... there is a clutch line replacement, fluid replacement, fluid additive, and Tremec swap. Most of the threads are in the 5.0 forum.
Thanks for the advice. i will look into the clutch line replacement. I dont want to swap my entire transmission. Has anyone upgraded the PP and solved this issue?