Car move off slow slips into high speed revs past 5K RPM then drops below 2K as gear changes. the 4th gear does not engage so the revs is as high as 4K depending on speed. ( I am on the Highway a lot ).

So basically the Transmission is shot 1 & 2 is bad and it does not go into 4

slippage, overheating, premature wear

...This was still a new van at the time and we were already spending money for major repairs that caused other need for repairs that were not under warranty. The engine mounts were always missing or broken somehow and presumably causing some kind of miss-aligning of the front wheels, pre-mature wearing of the tires, timing gear, and constant trips back to repair shop that seemed, still to this day, unrepairable.