I bought an Echo cs-300 for cutting landscape timbers and a few small branches. The saw worked great for the first few tanks and then I was cutting some peices in the back yard and it stuttered a few times now it only seems to open to half throttle. The chain will stop if add any force to the saw while cutting. However the saw will rap out if press the purge pump. I am not sure if the carb is dirty or the fuel is bad or what. If any one has had similar problems please throw me some help before the saw gets thrown.