2003 Acura TL Rattling

I have had my TL eversince I bought it brand new in 2003 and had followed all the maintenance at the dealership. However recently, I noticed that when I step on the gas, the car is more sluggish and alot of the times I hear a rattling noise in the rear. It seems to be worse or noticeable when the AC is on. I am not sure what this is. Also, I am wondering if I should continue to take my car to the dearler or just any old mechanic.

Are you absolutely sure that the rattling is coming from the rear of the car?
If your car seems sluggish, and if there is a rattling noise upon acceleration–particularly if the A/C is on–that could be “spark knock” or pinging. The noise is similar to the sound of a couple of pebbles rattling in a tin can when the can is shaken.

Does this car call for premium octane gas?
If so, are you using that specified octane?
If not, then you should do so, and that alone may resolve the problem.

If this does not help, then the problem could be related to spark plugs that are in need of changing, an engine that is running too hot, an EGR valve that is stuck, or carbon build-up in the cylinders. In “the old days”, we used to retard the timing to correct this situation, but I doubt that the timing on your car is adjustable. A good mechanic may be necessary to figure out the source of the problem if the car is exhibiting spark knock.

It is also possible that you have two or three unrelated problems. Cars are designed to last a certain length of time, and various parts are built to last different lengths of time. For instance the brake pads are designed for so many miles, the fuel pump for so many hours, the water pump or cv joints or any other part has its own limits. Any old mechanic is not recommended here, but there are some well respected and reputable ones listed on this sight, look around and find one you trust, and go to him and see what he or she says.