49cc Huasheng 4 stroke tuned for altitude?

Okay, so I have a 49cc HS motor that is 100% stock, and im running the stock air cleaner and carb. It ran great at sea level in Arizona and in Southern California, but I just recently moved to higher altitude and it runs like crap here. Here's the symptoms: will only idle with the choke fully on, and dies as soon as i turn the choke off even a little... UNLESS if you give it gas, WHILE you switch the choke off, it goes just fine, but when you slow back down close to idle speed, it dies again (unless you switch the choke back ON while riding)!!! So it seems like its running LEAN, especially at idle. Is this because of the altitude change? I took the carb apart and cleaned everything, and I don't see any gunk or clogged jets. Is there anyone else running this motor at approx. 5000ft alt? Did you have a similar problem, and what was the remedy? Does anyone sell jets for this carb and if so, WHERE? Thanks guys!

I found a thread on here that the HS carb that I have DOES have an air mixture screw and that its covered with a brass tamper cap. I drilled that out and found the air mixture screw underneath it...I've made a little progress but dang it I still can't get it to run the way it should. I tries screwing it all the way in, and then tried half turns out all the way to see if it had any effect on it. I got it to run with no choke now, but it's sputtery, irregular and still wants to die at idle. THere's no middle ground, it's either high idle, like its trying to get away from me, or dying. Maybe raise the float bowls?

Nobody? Should I post this in another section?