What does your new spark plug look like now, is it all black, do you know how to test for spark with the spark plug out of the cylinder, you need a helper to turn the key. I will assume you have coil on your spark plug, take a plug out, put it into the coil, ground the threaded portion of your spark plug to metal on the engine, start with the key and see if you have spark easily or sometimes or not at all, we need more information please, is your check engine light on when you are driving before??