growling noise

[wulam]

I have a 02 tacoma 4x4 v6
There is a growling noise coming form the engine area. Most noticable when vehicle is in drive, brake pedal pressed and ac is on(enigne loaded). noise intermittenly, and can be heard while listing to the exhuast. exhaust is tight an all belts and pulley are good, has anyone come across this. Vehicle has new timing belt, water pump and tiign belt idler, and nosie is still preset