I have an 87 yj 4.2 with mpi conversion. Would adding an intake manifold from a 01 and newer, do anything for the performance. Since it's supposed to be bigger and all the ports the same length.

Putting an even newer manifold than the 1991-99 MPI manifold on your older style pre-1991 head won't do that much good ...
Do yourself a favor and install a 1991+ HO head, then put on the better flowing 2001+ manifold if you want to.

I plan on doing the head conversion. Just saving up the money.
Thanks

:confused: :confused: :confused: Help i have done the swap but it will not move. i dont know where to start the trans or the t case. it did work for a little
down my driveway. but now nothing shifts into all gears makes noise like a little wine when you hit the higher gears. Before that it would not shift into anyt gears? any in put you ca offer would be great please

Auto or manual? If auto, check the fluid level on flat ground and in nuetral. Use mopar tranny fluid (ATF 3).

:confused: :confused: :confused: Help i have done the swap but it will not move. i dont know where to start the trans or the t case. it did work for a little
down my driveway. but now nothing shifts into all gears makes noise like a little wine when you hit the higher gears. Before that it would not shift into anyt gears? any in put you ca offer would be great please

:confused: :confused: :confused: Help i have done the swap but it will not move. i dont know where to start the trans or the t case. it did work for a little
down my driveway. but now nothing shifts into all gears makes noise like a little wine when you hit the higher gears. Before that it would not shift into anyt gears? any in put you ca offer would be great please

Your question is extremely vague and has nothing to do with a manifold swap, stupid.
Try clicking "Post" next time you fawking illiterate newbie ...
and not in this forum either!:mad3: