I have a 99 f150 w/ 4.2l & 85.5k miles. Ive had it for about a year and once in awhile after putting it in drive and going to drive off it would seem like it was in neutral rev a bit then pop in to gear of course with a nasty jerk that couldnt be good for anything. The other day I left my apt and about 1/2 a mile down the road it started jerkin a bit. Not like it was missing but as if it were going back and forth between neutral and drive. After that it has now gotten to where 7/10 after I put it in drive it seems to not want to get into gear. I will give it gas and itll rev then catch and jerk or for the first time which happened today being that I was in a parking lot I put it back in park and then drive again and it was fine. Any ideas as to whats up? The fluid/filter was change ~4000mi ago.

 

I know I have that problem with my '87 F-150. After it sat all night I will get in it and put it in drive and wait.........wait...........wait.......and finally it will catch. Mine, once it catches, it never comes out of gear. It also has 250,000 miles on that trans. It being a newer truck I would check the fluid and make sure it is the RIGHT fluid. Hope this helps.
-Matt