At cruise my LONG TERM fuel trims are +9,any other time (idle, wot) their around +3. Truck mods are: Trimmed butterfly (currently has stock I stalled) K&N filter (tested with stock paper) Flowmaster 50 exiting in front of The rear tire. Also has a mild tune (high fuel trims have been a problem before tune) Things I've done to try and correct the problem: Smoke tested intake and sealed all leaks except for the whisper of smoke coming from the throttle blade shaft. Redone all intake gaskets. Swapped modded parts for stock parts I've checked fuel pressure. 56psi KOEO, 53 at idle and 62 with ur foot in it. All seem to be within GM specs. Swapped out both MAF and MAP sensors for known good sensors. Removed PCV system from I take and plugged. If I unplug the MAF senso and run in "speed density" long term goes to negative 4! Major difference which says vac leak but I can't find one for the life of me. Anyone have any ideas where to go next?