Hi - I headed out the driveway to work the other day (cold start) and headed down the road to find that the transmission would not upshift out of 2nd. Drove back home and parked it. Hoping the problem would magically disappear, I drove it again two days later, still stuck. This upshift problem happened suddenly without any other previous transmission noise, problem, or anything.

I read the codes today. Code 17 came up indicating O2 sensor short - could this possibly be related? I believe the car is starting in 2nd, I tried to force 1st gear start and seemed to start in same gear (now I'm not sure if its starting in 1st or 2nd). Not upshifting at all. Vacuum lines appear intact but I need to check vacuum. Bowden cable seems a little slack at idle although the marks line up at the throttle linkage.... Is there a kickdown solenoid that coule be stuck? I removed the wire from what I believe is the upshift delay solenoid on the back passenger side of the transmission and no change. Any thoughts?
I will drain and remove pan/filter next to see if theres any debris....