I have an 04 dvx 400 that will run good for about 10 minutes then will start bog when giving it gas then will eventually shut off. It has the stock Petcock replaced with an on off reserve petcock. And i have checked to make sure the gas cap wasn't causing a pressure build up. I have cleaned the carburetor and drained and refilled the gas tank. I am stumped. Any suggestions?

It seem to run for a few minutes longer when it is cooler out, so i am thinking that it is something to do will temperature or pressure build up but i am not sure what.