my f450 is losing power and I was told by someone who heard the truck that it was a fuel injector gone bad because he heard a puttering sound. I originally thought it may have been an exhaust leak but he said no its def a fuel injector. I saw an article in Popular Mechanics that said I can use a Noid Light to test. Is this easy to do? I think my f150 has the same problem too because its puttering slightly and theres also a weird high pitched sound coming from under the hood mostly audible when I am idling that sounds like its coming from an injector?