Took my boat out today and all was running fine with my 1GM10. I was keeping it at about 1000-2000rpm when all of the sudden it revs itself up to full throttle and I can't back it down or choke it out! White smoke is billowing from my exhaust and I can smell oil burning. I'm still able to throw the boat into forward and reverse, hoping that the gear change would put the engine under manageable load again. Finally after a minute or so it does back down and I can choke it out. I see oil in my bilge and some splattered toward the rear of the engine/ near the shaft but nothing really apparent showing its source. What the heck did I break???