[:@]i am driving a 04 f-150 4x4.Iwent on a rosd trip sleding and i lost all power when i had the truck in drive but when you put in park you could rev it up.so i went to a mechanic and he told me the plugs where bad,so he replaced them and it seemed to be a little better.but when i left to go home which was about 600k it started to act up again when i would put it in passing gear and the engine would rev to 4 or 5 thousand rpm.the truck would jerk back and forth and have a lack of power.when you would back off the gas it would start to pull again.the mechanic also did a fuel pressure check and replaced the air and fuel filter.no engine light would come on while it was doing this.also about a week before i had my actuator and hub assembly repalced on both sides because i had a noise coming from the drivers wheel it sounds like a paper bag in the wheel.when i back off the throttle it goes away to load the motor up again.it sounds as if my hub is meshing could this part be a vacuum problem.and if i lock it in 4x4 the hub dont make the noise. any help would be appreciated please

 

Sounds like something didn't get put back together right when you had you front hubs rebuilt. The lack of a check engine light would indicate you probably have a problem with something mechanical. I would have the front hubs checked first. Most other problems I know of that would cause this would probably result in the computer pulling codes...your check engine light would be on. The hub might not be fully dis-engauging. Hope this helps.