Idle air is set by the tune on a 4.6 & can be adjusted with your hand-held tuner. Don't try to adjust your throttle body. If since it's been doing this for a while as you indicate, try cleaning the throttle body, especially where the throttle shaft goes through the casting. I also had Bama tunes and after loading a new one, throttle response was awesome but then would seem to degrade and not be as responsive as at first. I have no idea what caused this but for me, it was only a driveability issue, not power. The engine made very good mid to upper RPM power with Bama tunes, but they made daily driving in the lower RPM ranges more of a chore.
2007 Grabber Orange GT, 5 spd, 3.55's, CDC classic front & GT500 rear spoiler, JLT C.A.I. w/Brenspeed 93 tune, Steeda UDP's & CMDP's, Hurst Comp+ Shifter, BMR STB, FRPP Hot Rod cams, GT500 suspension w/Vogtland Sport's, J&M LCA's, CHE anti-squat brackets, Pypes LT's & o/r X - Next up, E-Force! :shiny: