I have a 01 that I limped around on with a bad vp-44. Just got the new pump in and I've noticed a few things since.
1) On a start up after a 14 hr or longer sit period the engines lopes only for about 3 seconds then it is fine seem to notice it more on a overnight sit than through the day.
2) The truck seems to have awesome power when the engine is cold approx 125 F and lower but as temp gets closer to 190 it drives more like stock. Truck has banks big hoss tuner on it. Intake and exhaust mods other than that it is stock. Maybe i'm expecting mountain out of a mole hill but just wish the truck ran same as it did cold.

Thats it I'm thinking the loping might be fuel related i bought the pump and lift pump package from midwest fuel injection. but i'm also running a holley blue. my fuel pressure always stays up around 22-25 and w.o.t. it stays around 16-18. I spoke with midwest fuel injection before hand and they stated that the pressures would be fine. I'm thinking that because the fuel pressure on the pump is not maintained at shut down i might be getting a small amount of air trapped at startup. was wondering if anyone else has had this problem before with the amount of fuel pressure i'm running. The power problem has me baffled though maybe a bad senser i have ran the self test and have had it hooked to a diagnostic scanner and everything shows a clean code history.Any input would be appreciated

 

I have experienced the loping after start up when cold. I attributed to not waiting long enough for the fuel to heat. If I make sure I wait until the light is out, never have the problem. I have also had it if I released the starter right before it catches, and it catches.....

One other thought is that your FP may be over driving the VP44.

Food for thought.

 

I've thought of that as well this morning though I started the truck and it hit off perfect. outside temp was about 65 f. I might do some playing this weekend and set up a fuel regulator. It would be nice to regulate a constant 14-16 psi going to the vp-44 regardless of pedal position

 

you may have a small fuel leak, some air in lines ????
try bumping the starter before start, and see if it gets better...