Check your fuel pressure... P7100 pumps are known for having weak overflow valves and losing fuel pressure...
True....Depending on the mileage it would be very benefecial to make a change in the OFV.
Also remember stock lift pumps are not efficent pumps for high performance then tend to come up short at high RPM's...
ACtually this is not correct..The factory lift pump will support plenty of power.However,if the fuel system is compromised by air leaks(which is a very common problem) the factory lift pump will struggle to maintain even at low power levels.I have personally seen factory pumps run into the 800hp range.
IMO what you have is a fuel system that is allowing air into it somewhere that is causing a lean condition down low and when the RPM's rise the motor can overcome it.The injectors you installed are not large enough to cause this problem at all.I would start by pulling the rubber boot off the lift pump plunger and unplug the fuel heater wiring.IF you find that either are wet/damp with fuel they are allowing air into the fuel system which will be one problem.
The next place to look is the return line that runs behind the P7100 and off of the OFV.Follow the hard line and you will find a small section of rubber hose that gets hard and cracks and causes air leaks also.
Another place to look in the engine bay is where the factory fuel lines cross the bell housing.Mopar uses a line that is a braided outside/plastic lined center which are notorious for leaks as the plastic gets old.
Next place to look for leaks is by following the fuel lines along the frame rails.As the trucks get older the steel lines fail as they rust and will begin to weep or show wet spots.Also try and look on top of the fuel tank basket as you will also find that the hoses there will fail with age and leak or possibly break off a barb fitting and it will leak.
Until you troiuble shoot the fuel system I would not look elsewhere.DV's can cause what your experiencing BUT usually when the have issues the truck will miss from the bottom to the top and not smooth out.I have also seen what you experiencing due to dirty fuel filter and/or pre-filter screen(pre-filter is located down on the lift pump assembly).
Let me know how you make out and I hope this helps.I spent HOURS redoing the fuel system on my old 12v and have seen many guys miss one little leak and it killed them for power..........Andy
P.S.-Also make sure you have no wet injector lines at their mounting points and the small brass washer hoops on the return lines are not leaking.