Engine is dieing and throttle is less responsive

[newob]

So I finally got my boxster s back from the shop and I have noticed and increase in a Problem that was somewhat present prior to my little fender bender.

The engine keeps dieing at low revs. Basically if I take it out of gear and coast into a stoplight the engine will cut out. Also when I first drive it when it is cold, the exhaust is a bit smokey.

This morning while driving to university I found that the throttle was also not responding very well. I would mash on the gas and it would not rev very quickly and it would do it jerkily? Idk it was weird.
My first thought is throttle body?
Perhaps if I run some carb cleaner stuff in it with the gas it would help?
Once it is warmed up it seems to do ok except for the stalls at lights.
How do I clean my throttle body?