I have a 2001 Ford F150 with the 5.4L. When going down the road and i want to give it a little gas all it will do is rev up to 4000RPM and stay there, it wont shift unless i let off on the gas. Just driving it nice it shifts nice, and it pulls my gooseneck 4 horse trailer just fine. I am thinking its the torque converter but i would just like any advise right now on what it could be. Thanks!

 

Moved to the appropriate section.