I just put new rings in my 2002 300ex and bought a newer head off a 2006 300ex and put it together. when i started it it idles kinda fast and within a min the whole exhaust was almost red hot. I turned down the idle but still got really hot. It also sputters when u try and give it full throttle. What could be the problem?

 

check the boot off the carberator that hooks up to the motor and make sure you have asolid seal