Can someone tell me please that if my HRX idle is off or sputtering a little what might be the cause of this? I have changed the spark plug, cleaned the air filter and removed the gas and put new gas in the tank. Also, how tall can grass be before this thing will shut off? Last weekend when I cut my yard down for the last time before it really get's greened up, I had the blade set to the notch just before the lowest setting and the grass was at about 1.5-2" tall and it cut off on me several times. Now I do have some pretty thick hybrid bermuda.....any suggestions would be great!!! I couldn't find an idle screw on this mower either and I am not going to pay $30 for their shop manual.....rip off!!