The BeeMan

Hey everyone, I just recently purchased a 1992 Toyota pickup it's a automatic 4x4 with the 3.0 motor. When I purchased truck I was told transmission was about to go. It would stick in either 1st or 2nd gear. I noticed the coolant was low due to a leak in radiator so I added some quick seal which stopped leak. The tranny seemed to be fixed. But the truck goes through stages where is hesitates, stalls, or sputters then acts fine again. It will idle for hours purring like a kitten. I check TPS it's seems fine. What am I missing?