82 CJ-5, swapped in a 4.0 Renix from an 89 XJ.
The knock sensor is not properly installed, but I am told this is not needed.
Used the Hesco Harmonic Balancer CPS setup

After the engine warms up (10 miles on the freeway) I get a governor type reaction above 2500 rpms. Where there is no power and the engine chugs and lugs above 2500 rpms heavy load, no load, at stop, on the road once it starts.
I replaced the O2 sensor during the swap, the Hesco harmonic balancer is slightly out of round.

Anyone run into anything similar?
I run into similar bad running 100% of time when the Hesco is set wrong or when I have a vacuum leak. But we were unable to find a vacumm leak

i had this issue befor with my 4cyl, worth check on your 4.0, the plug that went into the coil was bad and not giving full spark to the dist at high RPM, which also cause the cat converter to go bad causing same problem again later on