Just4fun1

Hey all I have a 2004 Lariat w/5.4 and 102000 miles. On a recent trip to NC (approx 350 mi one way) I noticed that after any length of time cruising hwy speeds with or without the cruise control on an initial kickdown to accelerate around those left lane riders I get a seriously hard hit from under the truck. Nothing ever seems to slip and I get no dtc's or flash from o/d light. The truck never misses a beat and takes right off. Just on initial downshift it hits HARD. This is also an intermittent issue as it didn't do it all the time. I've searched the forum for tranny issues but none seem to fit this issue. Any thoughts??? Thanx.