trans loading in drive and reverse

Weird issue with my trans that seems to be getting worse. In any forward gear and reverse it loads against the brakes, sometimes enough to stall the van in reverse. Seems to only do this after it's warmed up. I check the FIPL 0.992v closed and 4.1v WOT. It's almost as if the TC is trying to lockup or something. Also when I let go of the brake and start to accelerate it will "drop out" for a moment then go, like a looong gear change. Sometimes it will do the hard shifting thing as well. Is there some other sensor I need to be looking at? I did a search and came up empty handed, although the tach sensor seemed to be of interest. Can't afford to just throw money at it.