I have a 1992 Jeep Cherokee Laredo, with the inline 6 4.0l engine. Recently we did a motor swap, and swapped it with the same motor. The motor that was dropped in for sure runs, took it out of a Jeep I was driving prior but that Jeep was rusted out so just used the motor from it. Alternator, and battery both only a couple months old, maybe 3 months. Spark plugs and wires brand new. CPS is fairly new, idle air control valve is brand new as well. Prior to the motor swap, my old motor ran rough, sometimes idle was low and sometimes high, took a bit to crank it sometimes, but being that the motor had issues I decided to swap it with one I knew was pretty much good. Once the Jeep was put back together after the swap, we have tried numerous times to crank it but all it does is crank...crank...crank, but won't actually run. The distributor is good. Spark, fuel pressure, and compression are all there but they are all weak. The fuel pump works as well too. I've sprayed starter fluid in the intake several times and still only cranks but won't actually turn over and run or even try to run. I've checked everything I can think of for the past week and truly have no idea what else it could be other than the PCM. Prior to the motor swap my PCM had the voltage regulator go out so I just got an external Voltage regulator and ran it with the new alternator and never had anymore charging issues. The only two things I can think would be the issue now is the electrical connector to the IACV does have 2 bare wires that I plan to replace tomorrow, and lastly the PCM is the only other thing I can think of. Any ideas anyone?

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