99 F150 5.4 LT PROBLEM JUST STARTED. AT 55 TO 60 MPH AND YOU LET OFF THE GAS TO COAST THE TRUCK WILL LOOSE ABOUT 500 RPM IMMEDIATELY. AND MOST TIMES IT WILL DOWN SHIFT OUT OF OVERDRIVE INTO 3RD AT HIGH SPEED. HAVEN'T NOTICED IF ITS WHEN FIRST GETTING INTO THE TRUCK AFTER COLD START OR NOT. ANYONE ELSE HAVE THIS PROBLEM??????