i have a f150 4.2 and have changed the cam position sensor in it twice in 8 months. it went bad about a month after i replaced it back in june or so. after changing it the second time i heard the hamsters under the hood. for about a week. now nothing and everything is ok but i know that the sensor is going to be eaten again by the cam. what is causing this? is it the thrust bearings? is it the dummy distributor itself? i just changed out the tranny prolly cause of the sensor. i know airplanes. not trucks. help.