When I get on the sway and drive for say ten miles then get off and try some city driving my car shifts funny. It will get up to 3000 Rpms then slip some up to 3500 rpms then shift to second and it's a hard shift. What ahold I do it only happens after eway driving. I was think flush fill with new filter and gasket but have heard bad things about doing that people told me it will stir up drit in trans and cause problems Let me know thanks