Clicking Noise from Engine

Pontiac Sunfire, 1996, 118000 miles. My check engine light was on and I had repaired both O2 senors, a new exhaust and a oil change. This was all done back in March of this year. Now for the last 2 days my engine has been making this loud clicking noise everytime I drive it and cuts off on me several times. My check oil light and engine light came on, so I took my car to go get serviced and was told since my engine is making the loud clicking noise while running no one would look at it because the engine might drop. Do you have an idea what the noise can be? I'm at a lost as to what I should do and how I can fix this problem and idea?