If you had to hold the throttle blades open to get the engine to start I would think that would indicate your engine needs air (rich?).
In my aftermarket system you have options to increase or decrease fuel by a multiplier relative to temp . And you also have the ability to control the idle air control valve % relative to the temp as well. There is also a decay rate (in seconds) to hold after start settings relative to temp.
So if you have control of the base fuel multiplier and you have control of the ICA in theory I would think you either increase the amount of air (open the IAC if you have one) or lean out the mixture?
Just remember that I am a noob, I have only been messing with my current aftermarket system for a year or two now. So I am not going to tell you I am right, just that is what I am seeing from what I have learned so far messing with my setup.