i have a 2000, RX300 AWD & i just recently noticed a rattling noise from under the drivers side when i stop at a light, stop sign, etc... "Almost sounds like pebbles in a can"

but when i shift to park the noise stops. Anybody ever had this problem???? need help

It may well be your catalytic converter coming apart inside. Does it still do it when you put it in neutral? If it only does it in gear, have someone get in the car, firmly apply the emergency brake and FIRMLY hold the foot brake with their left foot and slightly adjust the throttle with their right foot, if necessary, to create the noise. Lay on the ground along side of the car and hold a yard stick to the CC and to your ear. You should be able to hear the amplified sound if that is the problem.

With a helper inside or outside, try to locate the source.

Salim