100% speculation. In fact more of an educated guess. Basing it off of me owning this truck and how it's changed over the years. Installed the mopar 5.9 pcm vs oem 5.2 pcm. It runs like a champ. All the torque I'd need. The 360 makes power lower especially with it built for low to mid range TQ in mind. It simply couldn't run with stock 5.2 fuel mapping. The fuel pump concern was the mechanic. Not mine. Seems that 38-39 psi is perfect by the response. I'm gonna sound like the fool but how exactly do I go about proper "fuel sync"

 

Also alaska doesn't really have much of a dyno here. Thanks all for the replies. I think the backfire was partly from heavy throttle and dropping a gear. It hesitated and then would go. Almost like a really bad detonation except it's a backfire around the header collector location. When I say lean I mean 75% or more "go pedal". My shift points have much improved as well since using a correct pcm for the swapped motor... Performance or not. I'm intrigued by this fuel sync though..

 

It is adjusted by rotating the distributor and you need a decent scan tool to do it. It's timing the injectors like how on an older vehicle you adjust the ignition timing.

 

Okay. That has been done. I watched him explain the process with the old 318. Good to know though. Truck runs good and successful swap so thanks again guys!