I currently own a 2004 Fx4 with the 5.4 which I absolutely love. I have owned the truck for 3 years and had no issues with it whatsoever. Lately however I have been experiencing a rattling type sound coming from the front of the truck only under a load when say merging onto the highway for instance. My first thought was that it was a ping due to bad fuel possibly so I pretty much ran it out of gas then filled with 93 octane yet the noise is still there. My next thought is maybe a tensioner pulley ....any thoughts or ideas would be greatly appreciated..Thanks in advance..