Guys, I have an Echo PB2100 which seems to run OK until I give it full throttle, and then bogs down (loses power). I've tried new fuel and oil filters, new spark plug, adjusting carb, fresh fuel and I checked the cooling fins which were clean. I have a suspicion that the strange-looking fuel tank vent may play a part in this problem, but I don't know anything about it and the owner's manual doesn't seem to mention it. Any ideas? Thanks.