The car runs good sometimes. Then it starts to act like it does not want to even pull a hill and half way up the hill things will just clear up. When the car is turned off it just spines over very fast, like it is not firing but if I wait for about 30 to 40 minutes it will start right back up and do the same things over again. I have put a new air flow meter on it and that did not stop the problem. What should I do???