I have a 07 F150 5.4 V8 with 53,00 miles on it. When it idles in say the drive thru lane at a fast food joint or after I accelerate a little bit while backing up in my driveway it starts to shake real bad. I have tried changing the oil and upgrading the gas. I ran some fuel injector cleaner. Still happens. My engine also seems to run a little louder than it should. Almost sounds like a diesel at times. Any thoughts on what my problem could be? I took it into a mechanic and he couldnt recreate the problem supposedly. Ran a diagnostic test and nothing. No engine lights come on either. So that makes it more difficult.