Knock....

[TjXiong]

I have been posting this a few time but I still don't have clue to what that has been causing the knock. When the engine is dead cold and I start up the engine there will be a knock the knocks. It does not sound like a tick. As I rev up the engine the knock knocks faster as I rev the engine into higher rpm. Once the car is being driven for a while the knocks seems to go away. But a little after the knock seems to come back. I'm not sure if its the rod/piston. 99 gs 420a motor. Any clue.... The motor is all stock. No mods. I havent take the oil pan off yet to see if there is anything.