Thought I would thank the very few who responded to my problem of about 300Miles per tank drop to about 150.

Seems it was a faulty brand new O2 sensor.

After I measured a fellow 245 owner's voltage and saw his fluxuate between .2 and .8 volts, and his green wire into the computer measured at .5 volts consistently, I had it confirmed.

My green wire measured .5 volts. The new O2 sensor with black lead connected to the green measured .02 volts consistently. Dead on arrival.

I really couldn't believe that a brand new sensor could be faulty. I suppose even if they test some units at the factory, they only test a batch of them.

I installed new plugs and changed my oil (which seemed to smell like fuel) and filled up a tank of 93 octane. Seem to be back to normal MPG so far. Idles nice and smooth again.

Hard to believe that faulty O2 sensor had such a dramatic negative effect. Now I know!

Jason
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89 245 'loaded' with a Great Pyrenees