Transmission Problems

I have a 2003 Astro with 42,ooo miles. About a year ago I started to leave a stop sign and it just started to move slow and jerking for a few min then took off. Like the Trans was slipping really bad, Its done this about 4-5 time since and the last few weeks i can feel it jerking going down the road at highway speeds. Today it started getting bad. Could this be the bands and if so can I adjust then? I was told on fords you can externally but they were not sure about chevy! Thanks for your help!!

there is only one band in that trans 4l60-e,,,it is used for 2nd and O/D,,,it"s not adjustable,,,,,,best guess is a filter problem,,,more than likely a converter problem with that low of mileage,,,,pan should be dropped and checked for damage.......