I have a 99 GT with an annoying metal on metal noise coming from the engine most of the time. The noise only occurs at cruising speeds and completely goes away if I push on the throttle or when the car is decelerating. I can only explain the noise as a tap tap tap noise - not a knock. I am wondering if this may be a timing chain tensioner-related problem. Also it is much more difficult to duplicate this noise by simply opening the hood and opening the throttle - much worse while driving. The car has 76k miles on it, and the problem seems to only get worse these days. Anybody have a similar problem?? or any suggestions??