1995 GMC Suburban White smoke from exhaust

I have been having a bit of an issue with the heater core hose fitting above the water pump, it leaks from time 2 time. I figured the o ring may have went bad. Now just the other day I went to start my truck and got a sound like the starter slapping against the flex plate/fly wheel and the truck would not start. Thinking I had an issue with my stater I tried a few more times and it finally started but the first few stroke were weak it seemed as if the motor wanted to stall. Then I began to get thick white clouds from my dual exhaust pipes. I immediately ran to checked the gauge to identify if the truck was over heating, but it wasnt. I felt for moisture at the exhaust and it felt dry. I also checked the oil dip stick after letting the truck cool off for about 30 min. And the oil was dark not milky. I also changed the fuel filter because I thought I pumped some bad fuel (watered down). What do you think?