Ok, I'll try to simplify this issue the best can so hopefully I get some good advice. Here lately I've been having a hesitation/popping issue when going to full boost/WOT when I stab the gas to the floor...if I roll into it she doesn't usually act up. I replaced the spark plugs...didn't help. I swapped out the fuel rail pressure sensor with two others that I know are good....didn't help. I checked all vacuum lines for leaks....nothing. I dropped the fuel tank and verified that there were no lose hoses, connections, or issues with the fuel socks....all good there. I replaced the fuel filter with a new one...no help there either. Today I put the car on the dyno to tune for e85, and had my tuner data log all the fuel related parameters...he noticed that the fuel pressure at idle was 66 psi. He also noticed that while going to almost WOT the fuel pressure would quickly drop off to ~33 psi around 5000 rpm, then jump right back up. We took the Kenny Bell BAP out of the loop and that made no difference with the idle fuel pressure. I unplugged the FRPS when idling and the fuel pressure jumped up to default 77 psi like it should....so that told us it was working like it should. The last obvious things to check were the FPDM's. Tonight when I got home I removed and replaced both FPDM's with two known good ones and started the car....the fuel pressure was still around 66 psi at idle. I swapped out the FRPS with known good ones, and still had the high idle pressure. At this point I'm sorta at a dead end with ideas of what to check next. The car runs like a top when just driving around, and pulls like a beast until it hits that fuel pressure drop off point. Anyone else have ANY ideas at all...even ones you think are crazy??? All help will be greatly appreciated!