I have a John Deere 165 with a Kawasaki 12.5 HP. It will run fine for awhile (a couple of laps) and then acts like its starving for gas and wanting to die. I did use some leftover (ethanol free) gas from last fall. I cleaned the carb. & thought it was gonna be good, but it started again, seems to be worse when the mower leans to the side like cutting lengthwise of a ditch. Any suggestions would be appreciated.