I was following my fiance home today, and passed her in a passing zone, hammering pretty good. After that she followed me another 2-3 miles, and we came to a stop light. When I pulled out she noticed a small puff of white out of the exhaust but went right away. Next stop sign same thing, but quickly stops as I accelerate. She said the truck never did anything while I was passing her.

Engine was at full temp, and air temp in the 80's here. Any ideas where I should start? Fuel Pressure? I have never seen anything on cold starts, or have any problems while driving, and power seems normal.