Bad Gas Mileage

My 2000 V6 is only getting around 15mpg. Seems to run fine, no codes or lights (except for the 32 airbag light I still haven't fixed). Any ideas? 98K miles and I've replaced the air filter and cabin air filter. I did find a gap where the silencer had been broken from the bottom up on the Air Filter Exit Pipe. I resealed this thinking it might be causing an intake issue and eating up the mpg. I haven't noticed a difference in mileage tho. Any thoughts would be appreciated. Alos, if anyone could take a look at my Driver Seat Module Post from a while back and offer any suggestions, I'd appreciate it. Thanks all.

Have you performed a tune up on the car recently? With 98k, you're probably due for spark plugs, fuel filter, fuel injector cleaner, MAF sensor cleaning, air filter, oxygen sensors, and maybe even a coolant temperature sensor. Any of these items could affect your fuel economy.

-Rod