I had this problem with my 98.5 the problem was the ground from the PCM to battery. If you take a look at your ground wires from your passenger side battery you can fallow one of them back to the PCM behind the air box. Take your grounds off and clean them up really good then connect to you battery and tighten down real snug. I have buddy that had his tranny rebuilt because his truck was shifting in and out of OD. after he cot it back it was still doing it cleaned his Grounds and she ran perfect. boy was he pissed. you might want to check this first before you go and stat buying sensors this will only cost you a Little of your time.