About 6 months ago i did a trans flush on my 88 F150 4x4. awhile after i noticed the trans starting to slip. i checked the fluid level and i overfilled the trans by about 1-1 and a half inches on the stick. i drained out what i had to drain out and checked the level and it was fine. now 2 days after its still slipping, worse than before. my question is can overfilling cause the trans to slip?

 

Not really. What kind of fluid did you use.