Have a 99 V-6 Camaro. the oil gauge has had a constant fluctuation almost a constant flutter. The oil pressure sending unit was replaced and the fluctuation continued. Now when the engine is slightly revved there is a tick or a slight knock (not at idle). Any thoughts where to start, could it be the oil pump?

Thanks in advance for any help.

 

Is it a knock or a tick sound that can make a big difference.