However, I'm not really sure that it is. Is it possible that it's somethin else if so, what? This is my first post and my first 5.0, I love it. I also have an issue that my check engine light goes on and off, and off and on, not so much when the car is colder in the mornings.... any idea??? Sometimes it seems to be missing just like, when i hit the gas it will be strong then a brief loss then back again..... someone please help. Much appreciated. Oh yeah, royal purple good as they say???