Ford Repair: 2001 Windstar, miss fire, filter change

Question
2001 Windstar, while driving it tends to studder/jump and not neccessarly when changing gears. It does tend to do it more often when stepping on the gas. I've been told it needs a transmition oil and filter change.

Answer
it sounds like u might have a miss fire , i want u to hold the brake very hard and give it gas while in drive , and if it studders it is a missfire if not maybe a chatter in the trans if chatter in trans change fluid and add a chatter friction modifer to trans , let  me know how u made out