I recently had the plugs changed at 95,000 miles. Now when I am driving down the road and I get on the throttle slow or come to a hill and the truck is starting to pull harder I hear a loud chattering or some kind of noise coming from the driver side of the vehicle. My mechanic is a 25+ year ford mechanic that runs his own shop at his garage. He is very good. I would like some in put on this. I should say something to him but I don't want to look like a idiot. Am just trying to research this to find out what it is.