My 1992 f150 wont shift stays in first gear but go's backwards and forward
My trans in a f150 wont shift stay in first gear
Sounds like you need to take it to a transmission shop. The first gear is apparently not engaging. The exact reason for this cannot be determined in a venue such as Blurt it. A transmission shop will be able to look at and inspect your transmission and give you a more definitive answer.
Mine is fine til it shifts outta first... Then its super hard to second and no overdrive.... POS fords....