when im driving my st170 and i put my foot down it gets to just before 4000 rpm and it is being restricted by something it judders when it gets to this point and wont let me go past it?
the car is not running at its full potential.
someone has mentioned it could be the mass air flow sensor because i have added a uprated air filter?
i have changed my coil pack and had new leads and new spark plugs.
if any one can help me please













