2002 Ford Explorer V8 "sputtering/Clicking" Engine Noise & oil pressure light says low?

In The Past Few Days I Have Had A "sputtering-almost Clicking" Noise Coming From The Middle Of My Engine. Its Loud When I Start The Vehicle Up In The Morning And As I Press The Acelerator It Generally Goes Anyway Or Stops, Until I Stop (like A Traffic Light) Where It Resumes. Now Today, The Oil Pressure Gauge Drops Out To Low When I Let Off The Accelerator (thus The Check Engine Light Comes On) And Goes Back To High When I Accelerate Again (sometimes). One Incident The Engine Shut Off While I Was Driving After The Oil Pressure Gauge Was On Low One For About 10 Min. After That Occurred It Took About 4 Attempts To Start The Enigne Again (it Didn't Seem To Want To Turn Over). What Is Wrong With My Vehicle, Please Help.