Defueling/ Stuttering at 20-25 PSI
 

I'm about to freak out if I can't figure this out.

Truck is an 01.5 CTD HO 6 speed 4x4. 180k miles

Mods : Edge Comp (old style), FASS, AFE intake, turbo saver timer, unknown injection pump mods, unknown injectors (it does have a slight haze at idle, so I'm betting either the VP or the injectors are aftermarket), gauges.

The only code the truck has ever thrown was a lift pump out of range code, I'm assuming due to the FASS

It is having the most hit and miss stuttering at around 20 psi, to the point that it is bucking the whole truck, more hit than miss though. When it happens, my fuel pressure (just before the VP inlet) never drops below 16 psi. It does it regardless of if the engine is hot or cold, but if it has idled at a light or something, it will pull right to 30 psi no issue, after a few moments, it starts to buck. I'm also thinking defueling, because with the Comp turned up, it pours smoke at low boost, and doesn't even haze at 20 PSI now (unless it is running good, then there is a decent cloud)

The wild card to the issue is that when I carry my snow plow, the underhood temps rise (the air creates a vacuum in the grille, my coolant temp stays pretty normal, but my outside air temp will read 100 when it's 40 outside. When this happens, the problem goes away.

The other wild card is that if it is shut off and parked for 10 minutes, on restart, it runs great for about 3 miles, then the issue comes back.

All of this leads me to think it is heat related, but what sensor is causing it to defuel/change timing, but not throw a code? I pulled and cleaned the intake air sensor, and there is no change. I am trying to locate an OBD2 scanner so I can see if the sensor values are in range. As of right now, I am ruling out bad VP44 due to lack of codes, and it always starts on the second crank regardless of how hot or cold (down to 18 degrees so far) it is.

I'm going to change the fuel filter tomorrow just in case there is an issue where there is pressure but not volume (not likely), but what else do I need to be looking at?

You can take the edge comp off your truck and run it for bit and see if the edge comp is bad in your truck. Its worth a try.