I could be wrong, but this does not sound like a simple control pressure adjustment. I would not sit on this too long. Have it checked by a compentent tech who knows MBZ transmissions. Could be a number of different things. Of course, the ATF level is OK?? Start there..
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.