engine dies and needs choke to start

[Evil Sibhod]

I've got a 2003 gz with 5100 miles on it, I've only had her for 9 months now but I've never had any problems until this happened. Ok, this problem first occurred Friday afternoon when I was heading down a regularly traveled road to the ATM. I was lucky that I was stopping for a red light because as i slowed down the engine died and so i rolled to the red. Right after coming to a stop I just thought it was weird for it to die, because the light is about 2 miles from my house and the bike was plenty warmed up. At the light I tried starting the engine, but it didn't. It made a deep sound like it turned over once, but that was it. The battery is less than 2 months old so it's not the problem (would have been charged from the ride anyways). I tried starting it multiple times as I was pushing it around the corner into a parking lot. This didn't work at all, so I rocked the bike to make sure I still had gas (i was only at 120 miles and don't even worry about filling up for another 50-60, and I know for sure that my petcock was set to On and not reserve) I had plenty of gas, so i tried starting it with the choke, which did a little better, the engine turned over, but it was struggling so i tried to give it a little throttle which killed it. I got flustered so i decided to switch to Res just in case for some reason i got mixed up, and with no choke it pulled the same as the On position, however with the choke it started up and the engine was absolutely RACING. I immediately disengaged the choke and it slowed down to normal and I was off. I was a little worried about the whole situation and so I took back roads getting home, however I had to cross at one busy street (40mph) and of course as I turn onto it and head down for about a minute I could feel the bike slowing down and then speeding back up while I held constant throttle. The engine struggled and died once again as I was slowing to turn, so I tried starting it back up, but it would not cooperate until I used the choke again.

To test the problem out, I've had it occur at both fast speeds such as above, and also at 25mph in my neighborhood. I know Very little about motors both in cars or motorcycles, but I remembered that the last time I filled my tank the semi was rolling out of the gas station, meaning they had probably just got a shipment of gas or whatever, and so it probably stirred up all sorts of dirt and what not. It had been suggested to me to check the main fuel line to see if there was anything clogging it. I removed that and it was perfectly clean, so I put it back on and the problem still occurs. It seems to happen after the engine warms up because after checking the line I took a ride around the neighborhood and it took about 3 minutes for it to happen again.

My apologies for the length, but as I'm sure anyone of you would be, I'm worried heh. Maybe it's her way of getting revenge at me for listing her for sale...