I have a 98 Dodge caravan. 3.0 engine. It has a 3 speed trans. It was slipping when I bout it. I had the fluid and filter changed, shifted like a charm for a few days, now it slips in drive, but only after it heats up. first and second work fine,just drive slips. Some times it will shift into third some times it wont. After it cools down it will shift again until it warms up. I checked the fluid it is full. Any advice would be greatly appreciated.