[nelly]

Stu, the linkage that the choke cable connects to isn't sticking is it? or getting caught on the cable etc.???
There is also a screw on the same linkage assembly and is part of the fast idle setting. This shouldn't be touched really when setting the idle speed or balance up, but if it's been tweaked by mistake, then maybe that's buggering things about???
I'd drop it back to the dealer and have them check it out.