I had an older dozer break an idler and roll over on it's side when I was cutting a hill and did a similar thing. The only way I could stop the engine was to put it in it's highest gear, keep holding up on the blade lift and hold up on the rear ripper lift. The combination of all three was enough to choke it out. Otherwise, I was baffled. On that old tractor the only kill switch was a lever you pulled to shut off the fuel, but obviously that didn't help. Other than the previously stated broken idler, it just fouled the plugs in the little 2 cyl pony engine that started the diesel engine (I told you it was old).
Glad to hear you weren't hurt! I wasn't there, so I don't know how it was laying, but you may have been able to kill it by holding the FEL until it stayed on bypass and put it in high gear and pop the clutch. However, like I said, since I was there, you may have torn up your tractor trying to kill it that way.
