'94 plymouth voyeger stalling

My '94 Plymouth voyeger runs great, but stalls when put in gear. At first it would do this after a while of running, as if something was hot. then it would do this. It has 177 ,000 miles on the van but Supposed to be a new trans. was put in 11 before I bought it, now being two years ago. If I race the engine, drop it in gear(forward or reverse) it goes, 90 to 0. So, no evidence of trans slipping, motor just stalls as it(trans) is engaged. thanks, Gov