What could cause a 1998 Oldsmobile Cutlass GLS to hesitate and not go into overdrive?
A new service calibration for the powertrain control module was
released to address a sag condition, as well as others. I recommend
receiving this calibration from the dealer. There are any number of
internal transmission problems that could be related to this
concern, as well as engine mechanical problems or ignition related
problems (spark plugs) that could cause this condition.