The previous response as to what the Cam Sensor does was wrong.
The cam sensor is what provides for the correct timing of the fuel injectors. The crank sensor controls spark timing. An engine will run (although not always very well) with a bad cam sensor. With a dead crank sensor, you will have no spark.
Often (more often than not, in fact), the cam sensor itself will be just fine. The problem, in that case, is that the magnet in the camshaft sprocket (which the sensor gets its reading from) has flown from it's home and is no longer doing it's job. That being the case, a new sensor won't do a thing for you. The better thing to do, would be to remove your old sensor and slowly turn over the engine, looking for the magnet as you do. Keep in mind that since the camshaft turns at .5 the speed of the crankshaft, you'll have to turn over the engine twice to see all of the crank sprocket.
As for the new idle problems, perhaps the computer just has to learn and adjust to the new unit? This could possibly be made worse by the somewhat random timing of the fuel injection.
And speaking of that, if the car seems to run worse than usual when you start it up, shut it back off, wait a minute, and restart it. Having no signal from the cam sensor, it has to make a guess as for how to time the injectors. Some guesses are better or worse, so it may run better after another try or two.
Good luck with it.
