Idle, Choke, and Backfire?

[2003gzsc]

I have a 2003 GZ 250.

So on my way to work this morning my bike ran out of gas. I walked it .25 miles to a repair shop that doesn't sell gas. The guy gave me a gallon of 93 premium non-ethanol gas and I was on my way. Rode down the street to a gas station where I filled up on 93 premium non-ethanol gas.

Now, here is the problem I am having (I have never had this problem before and did not have it prior to today's events). 1) In order to keep my bike idling at a normal rpm, I have to have the choke open all the way. Otherwise, it will stall out. As I am riding I can close the choke and accelerate fine, but if I brake or slow down, the bike stalls out. I then have to open the choke all the way and and start it back up. 2) When the choke is fully open, it does not idle at a high rpm, but at a normal rpm as if the bike is warm and the choke is closed. 3) If I rev the bike while in neutral, it backfires once or twice as the rpms slow down.

Any idea what in the world is going on?