My check engine light came on after i changed the

Well you will first need to check you installation. The check engine light does not go on for no reason especially since you say the car isn't driving right.You should start by checking to make sure that there are no vacuum leaks from when you removed the intake manifold, be especially attentive to all the small hoses.The last thing on your list to check will be the spark plug wires, make sure they are well seated on the plugs.