So its November in Colorado. The temperature is officially low for the next few months, and my 22R is complaining. My gas mileage has dropped from 12.5 average mpg to 10.0 mpg. Unacceptable. Here are the symptoms: Excessive backfiring, exhaust smells of gasoline, and of course gas mileage. This leads me to believe that the engine is running rich. After briefly consulting the 'ol Toyota Truck Repair manual, I dont see an easy way to adjust the mixture for this altitude and temperature. Carburetor is stock, as are ignition and fuel systems. Recently, I converted to a DOA Racing Engines dual row timing chain, and have recently checked the timing. Spark plugs and wires inspected and gapped properly. I will admit to a few exhaust leaks... So... what systems should I adjust/repair/replace to solve the problem? Thanks for the insight.