Multiple Cyl Misfire

Here's the short story:

'00 XJ
Did not have the issue a month ago.
Motor threw the #5.
Swapped in a block from a 95, kept all the late model stuff (coil rail, etc).
Block in donor vehicle ran perfect.
Now, from the minute the new motor was put in, I get a multiple cyl misfire under load (hills) or above 3k RPM.

Every sensor from the '00 was kept. Again, this issue didn't occur in the donor vehicle or in the existing vehicle with the old motor prior to the motor going out.

I've talked to a few people, and the suggestions so far have been:

1. Swap CPS to Mopar one
2. Check for vaccuum or exhaust leak at manifold and re-torque bolts
3. Swap Cam Sensor
4. Swap PCM

I have to wait until this weekend to buy any parts (payday), but I thought I could get a head start tonight on any grunt work. So, I was hoping I might get some advice on things I could look at.

Thanks!

Did you use the 2000 head? How'd the valves look? compression test or leak down test

Everything looked great. Compression test was clean. Engine ran perfect as a daily driver for the previous owner.

Did you put the head off the 2000 onto the 95 block?

That coil could be shot?

Sounds like timing or coil, could also be low fuel pressure

Did you keep all the 2000 electronics (injectors etc)

Head is from the 95. Intake from the 2000, all ignition/sensors from the 2000.

We thought it was the coil as well so I picked up a new coil rail. No change.

We put a fuel pressure gauge on it and hammered the crap out of it and under load. ~49lbs sustained with no noticeable change.

Even under the old motor, I may not have had the CEL's, but it was always sluggish as hell. In an attempt to fix it, I swapped out every darn sensor I could get my hands on including the CPS and TPS, new 4 hole injectors, NGK plugs, O2 sensors, etc. Never made a bit of difference. Finally when the motor blew, I figured it was related to the '00 block that everyone complains about. Now, I have a known good motor and its running sluggish and now I have multiple misfire CELs. I'm not sure if they are related, but thought I should mention it.

The CPS isn't a Mopar, it's an autozone special, so it could be garbage. I thought about possibly getting the Mopar. But I also hate just blindly swinging at things since I've already spent so much money doing just that.

At this point, we're considering tossing in a '98 harness, distributor, coil and PCM from a rig known to be running perfect and toss out all the '00 stuff. But, who knows ... its not guaranteed to fix the issue.