Just bought a 99 Ram 1500 Van with a 3.9L w/ a 3 speed. tranny. When I take off from a stand still sometimes it feels like I'm spinning a tire but I'm not. Then sometimes a few seconds after take off or after slowing down for a turn it feels like I'm running on rumble strips for a sec or two. Just put a 24oz bottle of Lucas in and drove 10 miles home, but it didn't seem to help. The van has 58k miles on it and has a trailer hitch. Not sure if it was part of the conversion or if it was added later. Could it have possibly been overworked by the previous owner? I bought it from a small dealer who buys cars at insurance auctions. It was a victom of a fallen tree limb so I don't suspect anything hidden.

 

Your low/reverse band in the tranny might be due for an adjustment. If it's too loose you'll get slippage.