Front dif
 

I have an 05 mountaineer premium with the 4.6L AWD. I am having a problem when I step on it it makes a grinding noise and pulls to the right I let of the gas and from then on it does it when ever I push on the gas just slightly until cruising. When I put it in park and shut the car off it resets and if I am gentle on the throttle it does not happen. No lights come on and I have tried turning off the trac control with no results. Any help here would be great. Thanks in advance.