Yes you might want to forgo the cruise control in hilly areas. Let a little speed roll off on uphills-it may not even be much-and avoid the downshift.
If you have a tach you may be able to tell if converter is locked or not especially with four speed automatic. Get a feel for it in top gear on level road at cruising speed. Gradually feed in a little throttle. Not enough to force downshift to 3rd. At some point the converter should unlock and revs increase several hundred. The step isn't as much as a full downshift.
