I have a 2005 Rancher 350 2wd. It starts and idles with no problem. When I shift into 1st, it runs well for a minute or so, and then runs roughly and bogs down like it is starved for fuel. If I shift into the higher gears, it seems to run more smoothly, but still bogs down. If I let off the throttle, it runs smoothly again, but then bogs down. It's a lot like when there is water in the fuel, where the engine rpm fluctuates from high to low repeatedly. I drained the fuel tank, and added new gas, but it still has the same problem. Also, on the carb there are three lines (I assume vent or vacuum). One of the lines is broken, but I don't know if this has anything to do with the problem. Any ideas?