One problem related to transmission sensor has been reported for the 1998 Ford F-150. The most recently reported issues are listed below.
In cold weather, a 2-3 slip detect occurs on moderate hills at low acceleration. The first two times the truck was inspected by dealer, I was told the problem was the external transmission sensors, and the slip detect code was removed from the vehicle computer. Problem is re-occuring as the weather warms up, but slip detect code not being stored in computer. I've referenced TSB 99-9-6 (NHTSA item sb606428) to dealer, but have been told that the TSB is irrelavent and the transmission pan will have to be dropped to inspect the internal sensors at a cost of $1,200. Please (if possible) send me the full text of TSB 99-9-6 and/or NHTSA item sb606428 so that I may use it as back-up upon my next visit to the dealer. I will also let them know that I've filed an issue report here at the odi. Regards, eric slan.