1990 Plymouth Voyager

I just bought a 1990 Voyager with a 91 Plymouth Acclaim motor in it (4cyl).

When I start it sometimes it will run fine and other times it seems like it
is loading up on gas and runs rough and rich.

I have replaced the throttle sensor, MAP sensor, computer and in desperation
the entire throttle body and it still runs like crap. It has new plugs, wire
cap and rotor also.

Any ideas where to go now??

I did drive it to Kentucky last week with no problems but the return trip to
Michigan was a real trip. Thanks for any and all input....Brian