I have a 2000 bravada and it will shift out of overdrive when over 55 mph after driving it for around 30 min or so. First I will notice the torque converter disengaging and then shortly after it will jump into 3rd. No load on the vehicle. Shifts fine when doing it. Just jumps out of overdrive. Replaced the TPS and the MAP sensor as well as the MAF. Any help is appreciated.