Well it was bleeding down rapidly at the very start, before I started replacing parts. After the new reman infectors, new regulator and new fuel pump, it’s much better now. However, it still should hold pressure, lets say at 50 psi for more than 5 minutes. My 2004 Durango with 198,000 miles holds at 60 psi for at least 45 minutes. But I got to thinking about it and regardless of it losing pressure now much slower, the pressure is there and up to spec while it’s at idle but it still has a very bad miss, very rough idle with engine shake. Thats from a cold start to warm up. I’m still thinking it’s something internally wrong.

 

I totally understand the concern about a rapid bleed down as that's generally a sign of an injector stuck open or something like that. But TBH the numbers you're seeing now after the replacements dont sound alarming.

Being that all my manuals and such are packed away due to our move, I tried googling the spec. Not sure how accurate the numbers are, but I did find some info here:

https://www.fastfieros.com/tech/fuel_pressure_L67.htm

It seems to prescribe 2 tests:
-1st to measure leakdown for full pressure to be no more than 5 psi in 10 minutes (sounds like you're about half that rate)
-2nd to bleed down to 10psi and have no more than a 2 psi drop in 10 mins


Back onto your miss - are you 100% sure all 6 cylinders are firing when it's doing this? If you're hearing mechanical noise, I wonder if perhaps you've got a lifter that isnt pumping up? Wouldn't seem to explain really high fuel trims though. Any change when you unplug the MAF while its doing this?

 

No, I’m sure their all firing. I do know the Front very right plug and back very right plug are both more “white”, the 4 look normal. And with my original MAF when I unplug it, it almost immediately kills the engine. I even cleaned it with MAF cleaner, but it wasn’t dirty. I put the USED MAF in and got the same results. Think I mentioned earlier that I also tested the CAT, it’s good, it’s a High Flow CAT, that I purchased a few years ago. Anyway, it’s fine. With ALL the replacement parts and testing, it still runs, idles extremely bad. I do also know that my fuel trim numbers back in March were normal, single digits. About 2 weeks ago, going along about 60mph on the the way to work, it suddenly ran really bad, NO warning, no gradual signs. It was instant.

 

Well I’ve decided to sell my car, posted it in the classifieds and also have ZZP coil packs and wires for sale, also a spare PCM.

 

An ICM going bad will lead to misfires. From all the work you have done I'd go to the parts store and try a new ICm, it's 7 bolts and easy to swap out and check if the car runs better. If not return it. That would be my best guess on what is wrong