2001 supercrew f150 54engine when first driveing and go to stop fells like brakes are jumping in front end jerking motion. push on brake and its hard to push like it locks up. after stoping and going again abs light comes on and brakes work fine. brakes are hard till abs comes on any advise.

 

Suspect faulty or dirty ABS sensor. Do a search for something like "cleaning ABS sensor" or "replacing ABS sensor" you should find all kinds of useful info on this.

 

ok thanks ill try that idid replace left wheel bearing hub with junkyard one seem like it started after that after couple weeks of being on can u clean them

 

You can clean them, but thats not a guaranteed fix. If its bad and not dirty your going to have to replace. The good thing is they are not too expensive.