Loud Engine noise from my 99 solara

Hi, just wondering if anyone knew what the problem with my car could be. When i first start my car in the morning it revs around 3200RPM and make a horribly loud noise ( kind of like a vacuum sound ) the noise will quiet down after the car heats up but my idle drops to about 700RPM and the oil lamp will flicker on and off. But then as i drive and give it gas the engine gets loud as i give it more and more gas.

Any help/advice would be greatly appreciated.
Thank you