I have a 95 Cutlass Supreme with the 4T60-e with about 120K on it. Has been working fine till yesterday when I stopped after being on interstate for about 2 hrs, it starts out ok but goes from 1ST into 2nd ,then right away into 3rd. Its only in 2ND about a second. I checked the fluid an it was alittle below the crosshatched area. Added fluid and still shifts thru 2nd too guick. It also seems to vibrate when slowing down slowly at low speed.
Now I have the pan off to change fluid and filter, and was wondering if there is anything I should check out while the pan is off.
Thanks Ron

Check for metal in the pan.