My 1999 OBS 5mt Is only getting about 23 highway & 17 or less city mpg, even with ginger driving. The plugs are ngk iridium gapped to .43. Wires are ngk. The fuel filter has less than 5 k on it, I did replace the front O2 sensor with a Bosch unit. I've heard that these cars can be rather picky about those... But, I'm wondering if my maf sensor isn't bad as well. How could I tell if any of those are my issue? I've got an obdII scanner, so if anyone has the O2 sensor voltage parameters, that might be usefull. I apologize for my grammar, spelling & sentence structure, it's late. Thanks in advance.