Hello,
I am new to the forum but have spent a lot of time reading threads on here and have learned a ton. Thanks for all the past help. With that said here is my problem. I have a 88 Cherokee that I just put a new/ used motor in, it was running fine when it was pulled from the donor jeep. Also an 88. I now have a very rough idle and after doing some testing found I have no spark on cylinders 3 + 4 at idle but if I rev it up to about 2000 rpms After stumbling and sputtering a lot it is smooth's out sounds good and I get spark. It has new plugs, wires, cap, rotor. I tested the CPS and was within spec. But I know that doesn't me everything. I did Cruiser54' ground refresh with no change. The jeep ran fine before the swap but was low on compression and had a bad lifter tic.


So I'm lost. Would a bad CPS cause this? Or is there something else I am missing?


Thanks to everyone for the help.