My 1999 saturn SL2 is idling high, temp gauge too low, then it gets real hot and sometimes the light will come on, and sometimes it doesnt, and steam pours out, and I take the water resavoir cap off a

SOURCE: My 93 Saturn SL2 intermittent stalling issues

I would look at the egr system. First pull the valve and clean it. If you have a vacuum tester this would be a good time to test the valve itself as well. When under load you should be able to see the diaphragm engage and hold and then release as you release the vacuum. If that doesn't work check and/or replace the egr solenoid. It's located on the driver's side of the valve cover and usually runs about 60$.

Yours is a common complaint and the above is the most common remedy. Outside of that you might want to check and clean the idle air control valve and the port where it's housed. If it is extremely dirty or something managed to get stuck in there that could affect you vehicle running at idle as well.

Another thing, even though you just changed the plugs, pull one back out and look at it. If is fouled with oil you might need a new valve cover gasket which if it's leaking badly enough will impede spark.

SOURCE: 98 Saturn Sl2 overheat

If it overheated without being low on coolant the first time you may have a themostat sticking. But I would start with a check of all the hoses for cracks or loose clamps. Also check leakage at the front of the motor from the water pump. It's hidden behind the a/c compressor but you should see splash marks on the hood if it's leaking there. For good info on how to fix it yourself try www.saturnfans.com. There are a lot of good tech tip articles for the S series cars. I lost a water pump pulley at about 90,000 overheated five times getting home. The car now has 230,000 on it and still going strong.

SOURCE: 97 saturn sl2 temp light flashing and low coolant

If the temp gauge is reading normal, the lights are flashing, and the coolant level is full, the level sensor in the coolant bottle is the problem. I'm a service consultant for a Saturn dealer and I've run across this many times.

SOURCE: eratic idle,stalling,hard to start

do tune up and clean throttle body see if that helps