Those engines have a couple of problems. First off is the check engine light on and if it is what are the codes. Could just be a maintenance tune up or could be a mass airflow sensor problem. And for your heat its more likely a clogged heater core. I would ate the heater core lie removed and flush the heater core first. Also have the heater core lines looked at to see if they are rotten and or leakingsweaty said:I have a 2000 Ford Taurus Wagon with the ohv engine. It misfires occasionally and gas mileage has decreased to 14-15 mpg lately in suburban driving. It has usually gotten 20 mpg. The heater also seems to take a long time to give out heat.