2003 Mercury Sable Engine Light Came On Car Med Device Told Spark Plugs Leades

My engine light came on, I have the car med device it told me spark plugs and leades. I changed them with the plugs set at 0.52 as instructed by manufacture lable unduer the hod. now the engine just races at 3000 rpm, Then it will drop and flutter and when I try again it won't start I've also changed out the Idle Air Control Valve. because it was stuck on open the valve inside I mean. Do you think it's getting to much gas and I should change out the injector control unit I think it's that little device attacted to the pipe before it gose to the injectors.