Engine was running great until it ran out of gas. When I got it restarted the engine wants to run away. RPMs just increase without you advancing the throttle lever. I took the top off the carb and see no apparent broken parts. The choke lever wants to rise as the engine RPM goes up. Holding the choke lever down seems to make no difference. I have noted that the slide on this particular carb will only go in one way and can't be rotated 180 degrees as I read on this site.
Any ideas what has gone wrong?

 

tear the carb down, clean it, put it back together and try it.....i'm not sure what's going on, but at least we can have you do the carb, and that'll give us a starting place to start eliminating culprits. but it does sound like the slide got stuck.