This morning I got a trans fault and only had 1st and 2nd gear.

I was on my way to the gym, and on the way there I felt a slip and all I was left with was 1st and 2nd. I thought it might be related to my edge so I rerurned to stock tune when I got to the gym. After I left the error didn't come back and the trans shifted fine. However, after work I was to 1st and 2nd gear and is still this way.

Any ideas on what may be happening? I had a fault code on my edge, but it said unknown. Thanks...

edit:2004 F150 4x2 4.6l 40kmiles