I have a 2000 GT, in the morning and especially when it's cold my car pings a little under light accleration. The Ford dealer told me to stop using 93 octane gas and that helped, however if I use 87 like all the manuals do it spark knocks under full throttle very badly. I have found a happy medium in 89 octane which has stopped the knocking at full throttle but it still pings when the engine is cold or when it below say 45 degrees. This car is stock except for a K & N filter. Has anyone had this problem or have any idea what causes this. I am the second owner and the other owner was an older couple that never drove it. It's a manual and it only has 27000 miles on it.