when was the coolant temp sensor last replaced?, that thing can cause alot of wierd issues. id replace that first and see if that fixes your issue. they are kind of cheap. And for the grey smoke, that can mean its running rich. check the voltage on your tps with a voltage meter, it shoud read, i think, .45 volts with the car off and the ignition on, if the voltage is significantly higher than your tps is bad or needs to be adjusted, in that case the computer is being told that the throttle body is open, even know its closed, causing it to run rich.