So... do I have to ask? what petcock do you have?

Possible stuck or misbehaving slide.  
Tap the outside of the slide area with it running.

Possbile dirt in a jet.  
Drain bowl into a glass.  Look for gunk.
Drop the bowl, look for gunk in the bottom.
Pull main and pilot jets to check for blockage.

Anything more and you are pulling the carb off the bike...

If you really like working upside down in a cramped area, you might get the float off, then you can get the float needle and seat off and check the little filter on top of the seat.

Well GUS, If the motor was warmed up you shouldn't have had to pull out the choke to have it idle,so I'm think it might be related to the float bowl level, could be the screen plugged under the float valve seat ,it could slow flow into the bowl and cause the type of problems your having .You might what to do as Stewmills ,said above first ,drain the bowl into a clear vessel and see if there's crud in the gas you drained.YOU could also place another vessel under the drain and turn your petcock on and see if you have a decent flow out the bowl drain , if not that screen is suspect, or your float is hanging up.(tap the side of the bowl with a screwdriver handle and test again)

If it sat for a while and you never cleaned the carb or anything, then it may be time for a good bath.  Have you (sorry if I overlooked it) opened the drain screw on the bowl to see if it drains clean or if there are bits of stuff coming out? You can do that without having to take off anything...just be careful, those screws can be crusted in there and if you fight it too hard you can strip the head easily if you aren't careful.

OK, so after work I took the old Dodge & rescued Ol' Sliver. Brought him home. I took Stews advise and drained the bowl into a glass jar.
Sure enough! Looked like some one tried starting a sand box in there. I took the bowl off ( I should took pics. darn) and it was pretty ugly in there. I turned out the jet and there it was! The jet was nearly closed off with some sort of organic material. It was late so I blew everything out good and put him back together. I turned the key and the gas on and he took right off. I rode about 10 miles without a hitch.

Lessoned learned tho. I'll be ordering a gasket set for the carb. and as long as I'm at it I may just take the time to swap out the jet as long as I've got it apart.

Oh, and batman; yes JIS! I've known about it for some time and have been meaning to get some screw drivers of the JIS variety. For now I'm making due.

Thanks guys!

No bout adoubt it Stew!  I'll take my chance in the morning and ride Ol' Sliver to work again. Nothing more satisfying than finding a real solution for a problem. It's the grey area I don't like.

Good point batman, I'd thought of that but hadn't made it a priority. I probably should. Beats setting alongside the road.