Okay man, thanks I appreciate it. I know the 90 4.0s have about 13 HP less (177 compared to 190) than the 1995 4.0s, however mine (the 95) is leaking some oil, uses some oil, and i'm pretty certain has a cracked engine block. My 1995 4.0 also has 212k miles and the Cherokee motor only has 127k (which is overall in better shape) which should be better in the long run.
I was just curious if it wasn't too difficult to convert from a 95 zj engine to a 90 cherokee engine. I know Chrysler made some changes in 1991 (like you said, TBI to MPI) and didn't know if it would raise more issues than it would be worth lol
don't be afraid to put the "fun" in "dis-functional"