check those inlet hoses. there's 3 of them, and they equalise the pressure across the supercharger at idle when the pulley is switched off. if one is leaking, it will cause a slight vacuum leak; or a pressure reversion, causing your engine to suck more fuel and less air, resulting in an overly rich mixture at idle and the chugchugchugging you mention.
they would be my first check point.
other than that, check your SU needle isn't damaged and flooding it at idle.

either way, it sounds like it's running overly rich at idle.

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mate thatd be bloody exellent, give us a bit of info when ur comin up or wateva and yeah, be good to talk to someone about whose done the same engine as im building, u may be able to stop me from doing things the hard way etc.
cheers mate.

have u checked your compression? sometimes when compression is down in 1 or more cylinders the motor can be rough at idle. with boost u may have burnt a ring or valve if u have leaned out. but maybe im talkin crap

from past experience on a s/c mini i knew, coud it be that the bearings are strving of oil as the boost is pressuirsing the sump by blowing past the rings, and the cugging is due to the oil starvation and cavitation.
long shot but possible.
also the s/c should be making consistant boost not risiing if a toyota ageze model, is it starving uder low revs and the secondries opening up making it run ok later on in the carb? might need larger idle jets depending on carb.
also sounds like dizzy or vacume advance.
with boosted angines i have always been told to lock the dizzy timming to prevent problems. lower hp overall but no tuning problems

Thanks guys, great info. Will check all the listed areas today. I seem to think that the needle in the SU may be bent or a little distorted.
When doing the dynoing and shaving the needle for fuel requirements, the needle resemble a thin sewing needle by the time i had finished and was very, very thin at the wedge end.
Does anyone know of any material other than brass that needles can be made from. I have recorded the increments of my needle in 1/8 inch sections and can fabricate a needle if need be... just don't know what to use...

Mate im not that experienced with carbies but from that post above it sounds like you are struggling to get enough fuel in the mix, maybe you should upgrade the size of the SU or add a second, it would be beneficial in other ways too obviously air flow

i think it might be the carby pull ur carby apart and wash every thing with petty in an old ice cream container. chek the needle and seat, chek all valves and crap. it sounds like theres a bit of #### in the neeedle, have a look and tell us how u go, that should getr u outa trouble.

thanks lads, I will pull the carby off tomorrow and strip it and wash everything thoroughly.
when I think about it, the bloody thing started happening after a particularly hard run up a long, steep hill... some crap may have gone through the fuel filter and is lodged under the needle or something- will let you all know anyway...

yeah I was away on Sunday/monday. And then I left my phone in someone elses car on tuesday.

Any day this week before 2:30pm or so, gimme a call before 12pm

I've just sent you an SMS now...

could be as simple as bad batch of fuel. as #### fuel can do wierd and wonderful things usally effects idling, as i have noticed on crappy fuel. how long has this happened? did it start when near empty or when you filled up last? just try a nice new full tank of premium and see if does anything.

my webbers were idling real bad and running poor at one stage, i thought they needed tuning, but after a another tank full they ran fine.