I can't figure it out..

[schooler94]

Hey guys, I just joined the forums, and I've been having some problems with my '07 GZ250. Last Thursday night I rode it to school and it was pretty damn freezing after class (High 50's, cold for me) and my seat was wet with dew. I hopped on it and tried to start it and I wouldn't turn over. The battery was fine, the starter was fine, but it just wouldn't start. So I tried to start it with the choke all the way on for quite some time before it finally fired up. I let it warm up for a few minuted and froze my ass off the whole way home with no problems. I let it sit in my backyard for a few days while I was busy working and whatever, then I tried to start it up and it wouldn't start again! It wasn't even cold outside, probably like 75 degrees. Anyway, whenever I would try to start it after that it would take somewhere around 10 tries and then finally turn over (choke all the way on) and whenever I would let off the throttle, say to slow down at a stoplight, it would stall on me! Even with the choke all the way on... so I took it home, changed the spark plug, didn't help. I looked at the air filter to see if it was dirty, it looked pretty clean, but I can't see the inside, and I don't have an air compressor to blow it with. The housing was dry and spotless though. So, I figured it must be the carburetor. I removed it by myself (with absoltely no prior knowledge of anything to do with motorcycles, just little knowledge of cars) with the help of a users manual on this site. So I removed the carb and took it into a shop to have it professionally cleaned. I got it back yesterday and put everything together, and added a new inline fuel filter. I put in a gallon of fresh premium gas and tried to run it and the same thing happened. So I carefully drove it back to the shop and thhey said 50 bucks to check it out and fine tune everything. He said it probably just needs to be tuned now, so hopefully that's it and I don't need anymore work done. Anybody know what else it could be than just a tune? Thanks