Any engine I've owned with a carb has been like that, more or less. That is 5 motorbike engines and my nitro engine (cars have been fuel injected). Oddly the 2 strokes were less defiant of throttle than the 4s. Cold 4 Stroke and full throttle = stall. Cold 2 stroke and throttle = splutter and then rev. (Hard core tuners, sound familiar? Too Rich idle? What a choke does.*)
Choke settings normally make the engine less likely to stall with some throttle, but more likely to stall at idle.* The basic choke restricts the air long before the venture intake to richen the mixture. Idle engines don't like rich and flood eventually, but will rev, though drive boggy, 'snatchy' and rough.
You can "choke" your nitro engine various ways, but it's usually just better to give it a few clicks of trim more throttle and crank it over on the pull start till it starts.
Most of it comes down to:
a) Engine is cold, metals expand at different rates, oil works at higher temperatures = stiff engine
b) Fuel evaporates better when it's hot in the cylinder/crank/carb. Cold engine, you need more fuel to get enough to evaporate (atomize) in the air (mixture).
Modern cars and a lot of modern motorbikes have fuel injection and electronic engine management, so you don't notice the engine being cold as much, the EMU (Engine Management Unit) takes care of the fuel mixture and... scary... the actual throttle of the engine based on a whole host of engine parameters but including engine temp and your throttle pedal (<-- you would hope), people with aircon, might note the engine rpm rising when the cooler or heater is on, yep, that the EMU upping your throttle to produce more power for the electrics.
* = Modern chokes and carbs in motorbike engines are much more complex than a nitro engine. Usually they are slider carbs with 3 jets, floats, vacum lines, heaters, and chokes, even decicated starter jets, that work in more ingenius ways.
