2012 etec wont idle.

[pugs]

I have a 2012 800etec summit that wont idle. Was in revy for three days ran good first day then second day started having issues. When I went to start it had to work the throttle to get it going then when I did it would pour out black smoke, would run good when on the throttle but as soon as backed off would stall and have trouble starting it all over again. Could it be o2 sensor? Bad injector? did same thing at low and high elevation. Any thoughts would be appreciated.

 

[snopro]

Did you try new plugs?

 

[pugs]

Looked at plugs pto side had some carbon tracking, and top of plug had some wear on it like it was vibrating in cap. Dealer told me today my boyesen rad valves fell apart so hopefully that was the issue and didn't cause any engine damage.