98 gt making strange noise

rod knock?

check the heat sheilds on your cats, probably that

my car ticks....its a lifter... rev ur car and see if the rattling gets faster

SILVERPAGT:

What you describe is classic detonation (or, pinging). Clean your MAF if you are running an oiled air filter. A dirty MAF can lead to pinging. Try running mid-grade (91 octane) or high test (93 octane). Depending on the quality of gas you have been using, you can try a bottle of injector cleaner (I suggest Red Line). Lastly, you can try colder plugs. The stock plugs (Motorcraft) are [AWSF-] 32's, 22's are one step colder, and 12's are two steps colder than stock. The [copper core] 12's are usually not in stock but your dealer can get them for you easily. If all of these steps fail, then you need to get a tune because you do not want detonation (aptly named) to go on unchecked or you will be looking at engine damage ($$).

Hope this helps.

Hey DaDDyGSpot!!! 2000 Mustang GT's don't have lifters they are Overhead Cammers. My rattle was the rear seat shoulder harness buckle banging againt the hard plastic side panel.