:confused: well i know a 98 4.0 would bolt in my 91 wranger. but would my dash harness fit and work on a 98 4.0 with it wire harness and computer?

nope, everything about the TJ interior and wiring is different than a YJ. Find a YJ 4.0 computer and plug it in, the 2.5 and 4.0 YJ's use the same interior harnesses and almost identical engine harnesses