I have a 36" Toro WB and ever since the middle of the summer my machine would nearly stall from time to time. It never shut down but for a couple of seconds it would start to shut down and then immediately go back to full throttle. It didn't do it all the time but I did check the fuel filter, spark plugs and air filter and everything was fine. I went out yesterday and at least 6 times the mower did stall out and I pulled the cord and it immediately started back up. Any ideas as to what could be causing this? Thank you!