Tokuzumi, to start off with that block under the AAR is a thermal heater, not a choke/stove. It's not connected directly to fuel so it can't put fuel into the coolant. The only years a choke/stove was used on a z was 1971-1974. It had a metal shroud bolted to the exhaust manifold, with an accordion tube connecting that to the air cleaner.
ElmoZzz, how do you know your car is trying to overheat? Are you going by what the gauge says? Are you sure that the gauge is accurate during these periods? When it seems to be overheating, try running a temperature check at the radiator with a thermometer or even a laser thermometer. If you have access to a CO machine, stick the probe into the bottle part way and see if it registers any CO. Is your coolant fairly new? I've seen coolant get very stinky if it's old and can sometimes smell like gas. The only way that coolant and gas can get together is via a head gasket breech, and that is rare for that mix. Check your oil and see if it shows any signs of fuel contamination. Z man of Washington