2001 cummins fass 95 about 6 yrs old. truck runs fine for 60 to 80 miles fuel pressure 16 to 18 lbs then sudden drop to 0 if u accelerate any, stop truck let sit a min or two start back pressure fine for 5 to 7 miles then back to 0. drove about 60 miles like this today. i have edge juice guages plus a 6 lb idiot light pressures are real.. any help???