Wow! Haven't though of that! When it happens, I only "blip" the throttle a little to keep it running, but I've never really "revved" it. I did figure it would be a possible vacuum problem, but the "gas build up" thing confuses me a little (and the first time it ever happened to be was in the summer, if my memory serves me right). Thanks for the suggestion and I'll explore this!I have the exact same problems you do. I went on the Scotty Kilmer website and he told me it is excess heat causing a gas build up in the engine. If you rev the engine it will clear out and run normally right? He said his Cressida does the exact same thing (he has an MX83!) He says a special winter gasoline formula causes this problem and to fix it would involve re doing the whole vaccum system.
fuel gets so hot it evaporates in the fuel lines. the fuel system is calibrated for the density of liquid fuel so the engine doesn't run. less of an issue with FI and return type pressure regulators (unused hot fuel dumps back into the tank to mix with cold fuel and dissipate heat through the tank) was more of an issue with carbs because of low pressures and lines ran next to the engine longer (mech. pump to carb) and a carb sitting on a warm part of the engineMine has idled so low to the point that it did stall but it would start back up. What is vapor lock exactly?