Auto Tranny Issue

[87Golfk2]

Hey guys, I will be cruising down the freeway and when i give it gas to speed up, itll try to downshift back into third(it is a spd auto) and it starts to free rev like it just slips between the 4th and back into 3rd but no issues shifting up just with the downshifting. Any ideas could i be low on fliud or just time to clean/replace the filter and replace the fluid as well.... Let me know what yall think.

[LG6R]

http://faculty.ccp.edu/faculty/dreed...ech/atf01m.htm