99 300 King quad running problem.

[Rio_Grande]

I bought this quad last year used off of craigs list. It has seen mainence work at the property and that is about it. I had to pull the air box to work on the starter over the winter and since it has developed an issue where it will start up and run fine for a while then starts sputtering like it is out of fuel then dies. Putting the choke on full will get me about 10 more feet. then dead will not restart althought the starter works fine now. I checked the fuel and it seems to be getting to the carb and if I let the machine sit for a hour it fires right off almost in a over fueled maner as it takes a bit to idle right. take it out ride it and it repeats the prior seires of issues. I have not pulled the plug yet but intend to today. It is as if something is getting warm and failing. Or plugging up.

Any quidance would be appriciated.