Hey......I have a 2000 f150 4.6 and when I get up to around 65 -80 km it seems like the truck goes into neutral and just revs up and I have to let it drop to 55 or put in neutral and back to drive before it engages again........can anyone help me out............Thanks ........oh ya just changed the filter and fluid and put lucas tranny treatment in.....it just started doing this without warning...

 

Make sure the filters all the way in. plus look at the old one. is there a small rubber o-ring still on there? wonder where it's at?
PS never add an additive to these tranny's. They are sensitive that way.

 

ya I forgot to mention I changed the fluid and filter after the tranny was doing this...........and yup took the old rubber gasket out first before installing the new one......thanks for the reply......