My vehicle won't rev over 4250?

nah idont think its a mechanical problem, i mean it could be but very slight chance if the vehicle allows the car to rev to 4250, chances are it could be an electrical problem with the MAF sensor, check the MAF on your intake to see that there isnt any corrosion, you could do a continuity check if you have a digital multi meter, if not chances are you should take it to a shop