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General Discussions about the 300M and other LHs

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 #395899  by EasyRider300M
code issue is lean condition bank 1

I replaced PCV valve and hose.
I cleaned MAP sensor.
I installed a hose clamp on passenger side vacuum hose.
I notice a strong exhaust smell from most likely excessive gas being's not a gas smell but a strong musty exhaust smell

Is it possible the plenum gasket is leaking...I have 94,000 on the car and never had the plenum off.

When I reset the code, everything seems fine for about 10 miles...smell is gone and mpg seems better
But after several miles, code returns and musty exhaust smell returns and mpg seems to suffer.

Any ideas for a solution of this issue before I bring it to a mechanic?
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 #395961  by Sneke_Eyez
Have you checked your oxygen sensors? Could be worth swapping the bank 1 sensor (I usually do them in pairs).
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 #395966  by EasyRider300M
If the oxygen sensor were bad, shouldn't I get a code specifically for oxygen sensor.

Could the plenum gasket be leaking?
I have never had the plenum off. Does it gunked up with oil residue?
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 #395982  by Sneke_Eyez
If the plenum gasket was leaking I would imagine you could hear it, it would be sucking air.