Bob R. 7/28/2010It's probably not related to the O2 sensors, as if they fail, the engine just runs in open loop mode and burns more gas.
It sounds like it may be a fuel delivery or mass air sensor problem to me, but that is just an educated guess. Try running a tank of gas with some Techron additive in it before going to a foreign auto repair shop that is Bosch certified. The Mass Air sensor is in the rubber tube between the air filter and the intake manifold. It (the heated wire)can get contaminated if you don't keep the air filter clean.