hey guys I just picked up my first Jeep! 1991 Cherokee 2 dr 4.0 5 speed.i start it up it idles great rev it up revs up good and comes down to about 700-750 rpms. Once it warms up it starts to misfire and does extreme surging almost dies. Throttle does nothing. I’ve read on the forums I’ve replaced crank position sensor, throttle position sensor, I had a code for coolant temp sensor, the previous owner had replaced it but the wire was tight so replaced the end of the harness, still no luck. I’ve tried disconnecting O2 Sensor while running still sputters. The previous owner removed the cat converter, put a header on it a bored throttle body and a k&n cold air intake. Please help!

Here is the link to YouTube for a video of the sputtering