When Jeep is first started it has a misfire and if left idling too long the light starts blinking until turned off again. Misfire seems to go away if you raise idle, with scanner plugged in while driving no misfires show up until letting off on the throttle to stop or slow down then numbers go up. Have tried replacing coil pack, spark plugs, cam sensor, crank sensor, cleaned/tested injectors, both upstream O2 sensors, IAC motor, cleaned grounds, tested compression 150 psi. Jeep had new motor put in September 2020 and light first came on in October 2020. Light comes on for about a week and then goes out, then repeats that cycle. Any suggestions on what else to try?

 

What was the year of the donor motor? Swap anything from the donor other than the engine itself?