Nissan Repair: 97 Nisan Serena overdrive, lockup torque converter, vacuum line

Question
while in overdrive the revs go up and down for about half an hour before going back to normal.  It does seem to get worse on windy days.  It is an automatic 97 Nissan Serena.

Answer
Deborah,

The enging has a vacuum sensor that provides load information to the computer that shifts the computer in and out of overdrive as well as the application of the lockup torque converter.  Inspect the switch for the lockup torque converter as well as the vacuum line that feeds it.