Chevrolet Repair: TRANSMISSION, transmission oil, clutches

Question
99 TAHOE 2WD SHIFTS BACK N FORTH N N OUT OF OVERDRIVE N BACK INTO DRIVE AT ANY SPEED WHY PLEASE

Answer
HI DAVID,THIS COULD BE LOW ON TRANSMISSION OIL OR THE CLUTCHES ARE SLIPPING IN OVERDRIVE CAUSING IT TO COME OUT OF GEAR GOING INTO THE LOWER GEAR..YOU MAY WANT TO OF COURSE CK THE OIL. IF OK TAKE IT TO A SHOP AND HAVE IT SCANNED FOR ANY TROUBLE CODES IN THE PCM TO SEE IF THERE ARE ANY...THERE SHOULD BE CODES FOR THIS .LET ME KNOW HOW YOU MAKE OUT AND GOOD LUCK TO YOU,,,TOM..