my 97 4dr/2.2 Cavalier's oil light comes on at about 800-900 RPMs and then goes off when above that. So basically i just see it come on at stop lights after the car has warmed up. I brought it to a shop that i trust because it was having additional problems as well, and after having the engine flushed and the timing chain/gears and the valve cover replaced the mysterious oil light still is coming on at 800-900 RPMs. We tried setting the idle a little higher but that didn't work. Any ideas?

could it be the oil pump?

Try checking all your oil/fuel levels... Oil pumps usually cause more serious problems such as not starting/turning over, but its still possible, wouldn't hurt to have it checked. My 98 used to have the same problem but it mysteriously stopped one day and hasn't occured again.