My 91Z runs really rich, i can smell lots of gasoline fumes while driving with the windows down, i have replaced the fuel filter, the cats, the carbon canister, new plugs and the works, what else could make a car run rich, and rob my horsepower ?????

 

Defective O2 sensor (I'd consider that an integral part of a tune-up actually), or maybe a defective FPR or injectors. Start at the O2 sensor.

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"So many Mustangs, so little time..."

 

The temp sensor could be bad making the computer think it is cold all the time therefore making the car run rich.
Craig

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84 Z28 305HO, 5spd, 220,000 miles, Edelbrock intake, Hedman headers, low restriction exh(w/cat), K&N air filter. Best 1/4 so far 14.649 at 94.77mph

 

91,

Those are both good suggestions, and you should also scan for error codes. Even though the MIL lamp may not be on, there might be some stored codes that will give you a hint about the problem.

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Later,
Vader
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"I cannot take this any more... Saying everything I've said before..."
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