I've got a 2001 24 valve cummins with airdog 2 df-165 with adjustable regulator lift pump, edge juice with attitude tuner and I recently installed a fuel pressure guage and my pressure is set to about 17 psi at idle and at wide open throttle it is dropping below 10 psi, I've allready replaced the pump and guage and I'm still having the same issue what else could be causing this problem?