Why is my vehicle is running extremely noisily?

I own a 1996 Chevy 1500 Mach III conversion van that I had noticed was running a little louder than usual. I then, after dropping a friend off gave it a little gas and the engine noise increased exponentially. The remaining portion of the way home I was not able to go above 20 mph without the engine running far louder than it should. I also noticed a slight squeaking in the sound of the engine and the loudness did not subside the remaining duration of the ride.