Use carb cleaner. I did when I first got the car. Bone stock, so there was still that oil line (not oil, forgot what it was for PCV??) hooked up.
TONS of OIL in the (3k mile, stocker) IC and Plenum/intake. Ran like ****. Stumbled hard core on tip in, etc.
Cleaning the IC made a WORLD of difference. You might be surprised.
How often (I think) really depends on how much you drive it, and if you STILL have that (useless) line hooked up/not plugged. And the conditions in which you drive it.
Every year, use the 'spring cleaning guide' listed in the TTA FAQ list. 'NEEDED' or not, just an important ritual. And fairly easy and quick.
M