My 86 subaru gl wagon EA 82 all wheel drive carbed engine runs really well when the temp out side is around 20 to 30 f and when i keep the fuel tank above about 1/2. fuel filter 5 months old. The temp gauge stays in the middle no matter what the outside temp is. oil about 35 (sometimes) mostly on 15 to 20. charge is good spark plugs less then a year, wires less then a year, cap and rotor new. Old worn hitachi carb but still idles and runs good. so my question is why when its colder does it run better. oh altitude is 1000 ft, humidity usaly hi in northeast pennsylvania. also 185000 miles on a rappy engine.