Hello all this is my first post i have a 99 auto mustang gt with 4.10's, predator tune, 70mm TB, flowmaster 40 series, transcooler. I have a problem say im going around 55 and my RPMS are around 2500 if i put it in neutral the RPMS will go from 2500 to 3000 and go down to 2700 and back up why doesnt it go down to idle? it goes away when i put it back into drive