Stalls should not be experienced on throttle slams, nor on normal flight maneuvers. They have nothing to do with the inlet (in spite of the tech rep's assertion otherwise!), and if they are common to your operation, they are because your fuel controls are set up too hot. IHL's comment on having to reset them with big seasonal swings is quite correct, and also with big altitude changes.
The garden variety stall (on a clean, unworn engine) is due to the fuel control having too much accel gain, due to the metering valve position. After cranking the puppy in as far as it will go, then some shimming might be necessary.
I would be very surprised to find that someone could turn the heater on and or the accel bleed valve and get a stall (it takes a calendar to time the accel with the heater on!) Is that what you wrote, IHL?
Contact me if you have persistent stalls when you do the checks, I will try to help iron it out.