I just test drove a 2005 f150 5.4L auto transmission with 86,000+ miles today. While driving it up hill at about 20mph, it felt like it was slipping. The dealership is going to have their service team reinspect it tomorrow. It almost sounds like this truck is doing what the first guy was asking about. Has anyone else had this issue at this speed or gear range. If so was it an expensive repair? Just trying to get some feed back to see if this truck is worth purchasing.