Can I benefit from an adjustable FPR with these mods?

[TBMounty50]

Ok, I'm on a serious budget and wasn't planning any mods, but here's what happened. I've already installed an open element air intake, custom cat-back w/gutted secondary cats and electric fans on my '98 5.0 Mounty with little improvement. I know those are minor mods and wasn't expecting much anyway. I'm going much deeper in the future when I can afford to. One day I decided to clean the mass air filament simply as a maintenance procedure. Then I started to hear detonation at low rpm under load that was not there before I cleaned the maf. I then filled up with premium fuel to see what happened. Within minutes the pinging was gone and the truck runs better than it ever has. Can I assume that the mods had little effect because the maf was dirty and it was a little too rich until I cleaned it? And that these mods leaned it out because of the lack of cumputer tuning?

My other question is this, can I bump the fuel pressure with an adjustable fpr for now and sort of trick the computer or is it smarter than that? That trick worked on my '88 TurboCoupe when I increased the factory boost level, I've never tried it on EECV. I can't afford a tuner right now but will get one when things get serious with the 331, cam, headers and port work later on down the road. Then I'll already have the FPR at that point too if I buy it now.

 

[Turdle]

The open element air filter is probably causing a lean condition.
Instead of fooling with fuel pressure I would do one of 2 things

Continue down the present path, but get out of the ditch and contact James at www.hensonperformance.com
You really need a good tune to help the open air intake, as now the maf is just "confused"

Headers are a must, plan for those also. www.torquemonsterheaders.com

The other choice is to put the stock air box back on before you do engine damage.

 

[TBMounty50]

Is EECV that much more sensitive than IV? This is the first OBDII vehicle I've really messed with. I thought the MAF was able to read and compensate, to a point, increases in airflow. That kinda is it's job. Open element really throws it that much?