Ok, so it's only done this the last few times of driving, it will shift fine into all the gears, but once it gets to O/D it'll shift back to 3rd, then up to 4th, then back up to O/D. It will only do this upon takeoff and will stay in O/D after the 2nd time, and will drive normally afterward. I didnt know if this could be a TPS or what? Kinda new to the diesel world so any help will be great. Thanks.