Hi, I have two issues on my Harmony 1011. First problem, it has been a while getting a lot of black smoke came out when operating. I tried 92 rated gas, changed the engine oil and spark plug but it didn't help. The spark plug look burn very dark and black deposit on it after just 2 times of mowing. Second problem was happened yesterday when I lowed the cutting blade deck down to mow, the engine start to slow down and shut down. If I raise the cutting deck up before it shut down, it would pick up the speed and running again. I tried it on the flat ground lowed the cutting deck down and it running fine. Any advises are greatly appreciated!

-Wil

-Wil