I've heard similar problems where the recommendation was to check the low-speed mixture. If it's too rich, then your engine gets clogged up with fuel when you're idling and you have to expel this when you open the throttle.

If I remember correctly, the way to test this is to run the car around for a little while, then bring it to a complete stop. If it idles at a decent speed, then slows down, you're too rich.

I'm sure there's a better way to check though, just providing you with what I remember for now

As far as setting your idle goes, take off the whole air filter (not just the foam) and peer into the carb. Keep increasing the idle speed (with the engine shut off!) until there's a 1-1.5mm gap. Remember to open the throttle before making adjustments to your idle speed or you could damage the needles

Hope this helps