The car is hesitating and when you make it hesitate for a long duration the check engine light flashes repeatedly on and off 7-21 times and then goes away. If you just drive it lightly it seems okay and the check engine light will not come on. Under load it idles a bit high for a sec and then drops. We ran a code scanner on it and nothing is imprinted in the computer to say what it is. Any thoughts?

Try replace the spark plugs (NGK only).