[BloodRedStang]

I'd agree with not trusting your gas gauge. After driving my car sometimes the gas gauge will lower then come back up a couple of minutes later. I know a lot of others who have had this problem as well.

I don't trust any of the gauges in mine.. oil pressure gauge says pressures too high, but it was a quart low.. temp gauge says its overheating, but its not. Gas gauge says I have a little over. 1/4 tank, but I just put 11 gallons in. Voltometer dances with the beat of whatever music I'm listening to.. you get the idea.. lol

Your cars a new edge right? Check for a cracked exhaust header, may explain the tapping sound. or an exhaust rattle but I think that would change from rpms. Also, might wanna check your cats, could explain it running rough and crappy mileage.