Check your cable at the throttle body to make sure it isn't coming apart strand by strand and stuck. If that is working fine, then check the adjustment. If that is OK then remove oil pan and check for black sludge in the oil pan. If you see only a slight bit of the black stuff, that is normal. Its the normal wear and tear of the lip seals in the transmission. If there is more than say a table spoon of black stuff you may have a sticky valve body. Change the transmission oil and add a good synthetic additive. After you do that shift it manually for warm-up and then check to see if it opperates smoothly in drive. If it still seems to skipp second then you may have a broken acdcumulator spring. I WOULD GO TO ONLY SOMEONE WITH GREAT DIAGNOSTIC SKILLS . Otherwise you may get talked into a new tranmission. The automatic transmission feild is filled with a bunch of big part replacers and not a whole lot of small part wisdom. Just my thought. Good luck!