The car runs very strong and is very good on gas, but it just started to rattle and vibration increased during the last couple months. It happens when I put it in D or R and apply brakes (at the light etc). Sometimes there is a low pitch rattle heard from under the hood, but I was unable to pinpoint it so far.

93 VG auto with about 110 kmiles, all stock.

Any ideas? Thx!

 

bad motor mounts would be my first guess

 

Cylinder misfiring??

 

Nope, all 6 fire like Aegis battleship...

 

I am with him bad motor mounts. check in the engine compartment for marks or any thing that looks new as far as abrasions are concerned.

Step on brake and put in gear then give gas and see if it happens.
Your rotor might also be warped.

 

Which rotor are you takling about?

 

I've never heard of an ignition rotor warping so I'd assume he means brake rotor

 

My car used to rattle also. It was the rubber bumper thingies on the radiator support that touch the hood when it is closed. They were worn out and the hood was loose, so it rattled.

check to see if this might be it.

 

This did not come to me before that the hood might be rattling... It sounds logical, as there are not so many moving parts around the car. The exhaust will be another place to look, I guess..