I have a 2000 mercury magnum 350 which is fuel injected. The exhaust smokes and it smells rich from gas I also noticed fuel in the water while running at the dock, it appears excessive .I also experience a rise in the idle r.p.m. after deceleration from a higher speed. Shutting down the engine and restarting the idle returns to normal r.p.m The most concerning issue is gas in the crankcase. The mechanic claims I had good compression before buying the boat. If the compression was good what possible causes could create this issue of gas in the crankcase along with the exhaust symptoms and if the mechanic lied only to get future business what possible causes would that create. The boat is tight and I unfortunately can not get to all plugs for my own test I am looking for possible scenarios before plunging more money into this engine. As usual your help is always appreciated and has saved me a fair amount of money. Work done so far new fuel injectors-throttle position sensor-fuel regulator-complete tune up. Thank you for your time
