mad 300M owner

I have 2002 Chrylser 300M. And it has been having annoying problems after problems. I am not sure if it is really bad service at my dealer or it is just the build quality, I just don't know. The most recent problem I am having is that when I turn on the car and put it in Drive without actually moving, there is this sound-knocking+sqeaky sound- coming from under the dash of front passenger seat side. So naturally I thought it was my sunglasses rattle against other stuff in the glove compartment, but it wasn't at all. Another problem is that when the car is moving at 1500RPM, there is loud vibration coming from under the hood. It only happens at 1500RPM. Does anybody know what to tell my machanic? They've thought that it was my CAT. converter, but even after installing a new one, problem is still there.

Say, I use to have an annoying little rattle that sounded like it was in the glove box too. What I found out was the air filter box sits right on the right inner fender next to the front shock tower and was vibrating against the steel fender. Turns out the two brackets that hold the air intake box did not hold it securly enought. I took out the air filter box and put a piece of foam between the fender and the plastic box, I used two sided tape to secure the foam. Once I did this the noise went away. Another way I could tell this was causing the problem is that the paint was worn off the fender where the air filter box was rubbing on it. Hope this helps...