So, I have my '96 854T with a hair over 75k miles and for the past couple of months it's been getting not so great gas mileage. I'd like to blame it on the "winter" fuel mixtures used in the city ("not more than 10% MTBE...") but I'm not sure.

What I'm seeing is fuel economy that has gone from a boug 18.5mpg (city) to 15.8mpg... if I am easy on the gas. I've replaced the plugs with Bosche Plats, and put a new cap/rotor on, as well as plug wires for good measure. The fuel filter only has 12k miles on it.

I very often smell a "rich" burn smell when the car first fires up in the garage every morning, and for the past couple of months have smelled that sulpher smell that you hope is another car and not yours. These symptoms and in the fall, the car had a mysterious oil loss (about a quart) that was never traced to the coolant or dripping (saw a cloud of smoke one time)... but never again, have me wondering what could be up w/the motor.

Are these symptoms common for an expired Cat? Possibly an O2 sensor? Would the OBDII box be catching codes for any of this? Any other suggestions before I take it to my very trusted mechanic? I like to do what I can myself before I call him, for the obvious reasons... but he's worth every penny (and more) that he charges for his services.

tia,

Scott_in_AK