shaking in park ..

My girlfriend and I just bough an '01 Intrigue a little bit ago and noticed yesterday that it was shaking while we were sitting in the car, while it was in park .. I'm not sure if it's anything normal or if it's bad, but I figured I'd come on here and ask .. It's not shaking much, mostly only noticable when you're looking for it .. thanks in advance guys ..

I had same problem its only can be 2 things well that i know off bad Battery or altenator when the car dont have enuf power it does this or it can be fuel problem.