82 Malibu shift problem

Hi, I just got an 82 Malibu with 77,600 miles, supposedly. It sat for years. The tranny shifts to 3rd way too early and the engine lugs bad. I have to keep it in 2nd til I go over 40 and then lift it to drive…when I finally remember. My repair guy won’t touch it cause the car is older than him and his tranny guy went fishin. Anyone on shore out there that maybe run across this problem. Tranny’s been flushed. Thanks, Dave

Have the throttle valve cable from the carburator to the transmission checked for proper adjustment. If the adjustment is off the transmission won’t shift correctly.