What would cause my 03 Matrix engine to vibrate only at in neutral or drive?
I have already ruled out the intake manifold by replacing it with the upgraded orange one, have put in a brand new set of Iridium spark plugs a run a full tank of premium gas with injector cleaner added..
Transmission and/or motor mount(s). Not sure if the Matrix and Vibes have a trans dampening mount or not? If it does get that looked at too.