1998 Pontiac Bonneville white smoke

-car has been great no overheats, runs smooth, 27mpg.....until 2 days ago went to start it made a clunk noise - try to start again and started just fine but a huge billow of white smoke and check eng light came on... hooked up to the computer device and it showed just one code PO301 misfire in #1 cyl....took out that plug and saw the gap was huge so regapped it at .060 and that cleared the code and no more smoke til a day later - today it starts fine and runs ever so slightly rough on idle but tons of white smoke that smells sweetish like burned coolant - took that plug out again and notice its slightly wet compared to the others - does this sound like the upper intake manifold cracking that Ive read about or head gasket or cracked head ??
Many thanks,Lee