I'm suprised no errors coming up. Make sure you have someone check your PCM and BCM for codes. Automatic transmission: 4T60E transmissions may drop out of drive while cruising, shift erratically, or have no second, third, or fourth gear because of a bad ground connection for the shift solenoids. Poor grounds also allow wrong gear starts. (1991-93) Recommend you go to a dealer and ask for them if you could access their bulletins for the correction. Your solenoid pack may also be wiped out. GM's 4T60E's were notorious.