Yes, letting the carbon built up to long is a bad move.
I pulled it off just now and removed the solinoid coil and the oring and used carb spray and a pipe cleaner to clean it more. I rolled the pipe cleaner around the valve seat area and got a lot of carbon out. Blew it out and assembled and installed and test drove and it is almost perfect now with a slight hesitation.
My wifey decided we have to go somewhere at 3 PM so I will take it off, tear it down tomorrow and soak it in some real carb. cleaner I have. It's some powerfull stuff and will eat the carbon out. I think I can save this IAC.
I think I will look at my lil' Ranger's IAC and clean it out. It has about 62K on it and may be carboned some.