I had the same problem with a 2000 150 Opti, but maybe not as extreme. If you got the plug sideways and didnt screw it all the way in, go to Advance Auto and buy a thread chaser for a spark plug, (10 bucks at that time) and screw it in with a ratchet. You have to work it back and forth, not just screw it all the way in. When you work it out, spray the shavings with WD-40 and keep the threads clean. I have no idea why the metal in the plug is made out of harder metal than the block. Really doesnt add up. Hope this helps, because I kind of like your views on here.