97 Taurus 3.0 Vulcan, ~120,000 miles. (200,000km)
Seems that my gas milage has gone -way- down recently. Anywhere from
14-19MPG, depending how much I'm on the highway. There are no fuel system
leaks, and the system holds pressure. Also the engine has a very infrequent
miss at idle when warm (maybe once every 5 or 6 seconds, not on every
revolution), and will occasionally ping on uphill grades (I fill from a high
volume gas station, and my other car has no issues, so I'm pretty sure it's
not the gasoline i'm using) No codes, no service engine light, engine is
always run with mobil-1 synthetic (although it's almost due for a oil
change), air filters changed recently, plugs and wires changed last spring.
I'm thinking maybe it's running too rich, due to... MAF sensor? Maybe a
cleaning with 99% alcohol and a Q-Tip?