97 Sable 3.0 transmission issue
 

Hello! I have a 97 wagon with a 3.0. The transmission suddenly stopped downshifting, it seems. Our problems started several months ago when every now and then, especially when stopped on a slight hill, the car would shudder when taking off. It very slowly got worse. Now, it seems like the transmission isn't engaging in 1st or 2nd when in drive. This symptom came along suddenly. Is there possibly a linkage problem or something. I replaced the transmission range sensor today with no changes. Are there vacuum lines on this year that I might need to check? BTW, the "O/D off" light has come on quite frequently since we've had the car and has to be switched off using the shifter switch. THANKS for all your help! Mike.