So about 500 miles ago I got a fresh oil change, new thermostat, new belt and new coolant. About 3 weeks ago I drove the car and it was fine, we parked it in the garage for as we where only needed to use one car. Started it today and started fine and ran fine but leaving the house I noticed the car felt a bit down on power and when I tried to accelerate out on to the main road I only was able to get up to 4000 rpm. When I let off the car let out a cloud of white smoke from 4000 rpm to about 2800. driving back to the house when cruising the car will do 45 about 1800 and 60 at about 2000 rpm and everything sounds normal but the the car is only getting about 30 mpg rather then the almost 40 I get normally. Before I started the car it was full to the line for oil, coolant looked fresh and when I got home the car still had oil and the coolant looked fine.
My quick list of possible problems are as follows Running rich- explains the lack of power at the high end, but the smoke is the wrong color. Vacuum problem- which would cause it to run rich, or be down on power. ring blow-by- would explain the smoke but doesn't explain the smooth (for a zetec) idle and under load running.
The car is not triggering a check engine light.
Where do I even start?