Alright guys, I'm quite literally at my wits end trying to figure out what the hell is wrong with my truck. It feels very similar to a misfire, but without the sound a misfire normally makes and it's not consistent. Its more of a thrusting/surging feeling as if it is accelerating normally, and is if i for a second lifted off the accelerator pedal, and then mashed on the pedal again, and then repeats several times like a rocking chair. Only happens under moderate acceleration and is much more noticeable going uphill. At WOT sometimes it feels normal, sometimes the truck feels like a 4 banger instead of a supercharged v6. And coming back from the valley the other day up rather steep mountain grade, supercharger was boosting full balls at 10 psi and it felt like I was driving a ford escort. At one point I could almost swear to hearing a ping and lifted immediately and just limped home. This leads me to believe the problem is either with fuel delivery or spark.
I have absolutely no check engine fault codes or any previous stored codes.
I've inspected the coil boots thoroughly and they look absolutely fine.
I changed both the fuel filter and fuel pump when I did the URD 7th injector kit for the supercharger less than 20k miles ago. Fuel pump is actually a larger 190 lph pump.
On the same hunch, I changed the fuel filter again last week with no change in the symptoms.
Plugs are also brand new as of last week. Old plugs looked like normal wear, greyish/brownish color. If anything there's a minor amount of carbon soot deposits and minimal electrode wear.
As far as cleaning goes, I seafoamed, cleaned the MAF, and cleaned the throttle body.
I've inspected and measured according to the FSM (resistance, voltage, etc):
1) Plug wires
3) Camshaft position sensor
4) Crankshaft position sensor
5) Air/Fuel sensor (Pre-cat O2 sensor)
6) Post-cat O2 sensor
7) Mass air flow sensor
8) Throttle position sensor
9) Throttle control motor (both motor and clutch resistance)
10) Pedal position sensor
I've also completely disabled the URD 7th injector kit to try to eliminate possibilities. And today, i pulled the supercharger off completely and went back to the factory intake manifold and bought factory NGK plugs. While far less noticeable, the damn problem is still there.
I have 3 or 4 injectors from the old engine. I suppose the next step I could swap half the injectors at a time to see if that's the issue? I have no idea how to test the fuel pressure regulator short of buying a new one, and at $140, that's a semi-expensive guess. So at this point...I'm looking to TW to see if anyone's got some more ideas.
The good news is, I found my pliers I lost a year and a half ago when I swapped the supercharger on this engine