Having an issue with Transmission shifting, NEED HELP/ADVICE. 2010 Raptor, 160k miles, Recent partial fluid & Filter change. When auto shifting in residential and side streets, 1/2, 2/3, 3/4 shift normal but from 4 to 5, engine revs like in neutral with throttle barely applied when maintaining a steady speed. If accelerating onto the freeway all gears shift normally with no slippage. What do you all think? I have verified proper fluid level, there was no debris or metal shaving in the filter or pan magnet. Fluid was not burned or discolored. Thanks, Jim T.