Im extremely unhappy with ford at this moment.
A couple of months ago I noticed the truck being sluggish. thought it was just bad plugs like everyone else but then all of a sudden it stopped shifting from 3rd to 4th. I took it in and it had no codes. I called ford and they told me they thought it was the tranny. I was floored. The truck isnt even paid off yet and the darn tranny is already blown???? It has less than 60k miles on it and has had the the required work done on it. After searching the net I found many many people with the same problem as me. Everyone of them has a 2006 and everyone of them are blaming an overdrive issue that causes it to require a complete rebuild. My family has owned nothing but fords. I bought my first one on the FORD Tough theory even though it had a crappy 3 year 100k mile warranty with no extended warranty available. That is a mistake I wont make again. When talking to ford corp on the phone they told me the solution was to buy a new truck. Im thinking class action suit. I have talked to many ford mechs that all say its a known fact at the garage that fords f150 2004-2007 trannies are junk!!! So now with an estimated repair bill of 3900 on a truck that isnt even paid off and has less than 60k miles I can say my truck is FOUND ON ROAD DEAD!!!! Here is a link to others upset with ford about the tranny issues. http://www.carcomplaints.com/Ford/F-.../transmission/

 

The retaining snap ring in the OD (4th gear in your case) accumulator tends to break in the 4R75e transmission. When this happens, the accumulator disengages the OD band and instead of 4th gear you get neutral. Most often you will also lose 2nd gear engine braking. The solution is to drop the tranny pan, drop the valve body, inspect for a broken clip and remove all pieces. Reengage the accumulator in the OD band and install a new snap ring. Reinstall everything, fill with Mercon V and you should be good to go. Less that $100 and it should be fixed, if those are your symptoms.