This might be a no-brainer, but...

Have you checked the air filter? Also, is the gas smell from the tailpipe or is it under the hood? Those green o-rings on the EHA tend to seep, and just a few molecules of fuel can somehow magnify to create the aroma of gallons of gushing gasoline.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280