my van was fine then started running rough on 1993 Chevrolet G Series Van (G20)

i was driving on highway just fine halfway up the mountain rd started running rough had to drop someone off could not find why it was doing it drove back down the mountain nice and slow once back on highway when you try to pickup speed it runs rough and rougher could it be tranny fluid

If it runs rough all the time you might a bad plug wire or fouled spark plug