2001, F-150, Super Crew, Lariat, 5.4 Liter, unknown tranny. My pick-up has always had a problem maintaining RPMs if towing up long inclines. At highway speeds 3rd becomes too high (slowing due to low power) and 2nd is too low (high RPMs), same for lower speeds, 2nd is too high and 1st is too low. The passing gear kicks in and I don't tow with the over drive engaged. Any suggestions?