Hello:

It sure sounds like a classic fuel pressure regulator (the thing you labelled cannister). A gassy smelling vacuum line usually means that the rubber diagphragm inside the cannister has torn, allowing leakage of fuel back into the vacuum line and full fuel pressure all the time. It's an easy fix, assuming that is the only problem. You might as well replace the plugs as they will be fouled. Don't do anything with your O2 sensor until you get the fuel pressure stuff sorted out-- it will meter out as bad because you are rich all the time now. Fix it soon so you don't make a mess out of your cat too...

Good luck-- let us know what fixes things for you!

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Herb Goltz, London, Ontario, Canada '92 245 w/102K mi