I mastered a hot air maf, a 93 subaru. singular point injection...(they stayed the same for 9 years- 85-93)
The CAI (went to outsiude air source, real piping- nothing in engine bay) pegged the fuel mileage to 38mpg all year round. I have never had anyhting before or after like it...
the 240 is inline and has no coolant in the intake. This could be the anomoly for you. whatever works.
the subaru also has one long runner, across two heads, also single port. It even roasted in the winter..(all the crazy FI hertz). I went as far as blocking coolant from entering the base of the spfi unit, that is when the 38mpg pegged (reset ecu first)
maybe find a heat rise for external of the engine intake, and continue to get air from outside (wrap it?) as the engine with cool air is gonna be a winner for alot longer with it. hot air is thin, it reduces power, press throttle more, more heat.. the cycle sucks until engine fail prematurely.
be good to those 240 cylinder walls.. cool air in is a part of it.
not to sound confusing... in short, let the heat rise happen last second. find a way for the actual intake on the engine to stay warm, (tere should be a sensor there), and all is good. you described the wild flailing gas metering of an inlines dangling hanging in the willywags intake manifold perfectly.