96 Sable Overheated

My wife's car overheated yesterday morning. The cooling system sprung a leak and ran out of water. I put more water in it and tried to start, but it only cranked and sputtered...

I then checked the oil level and it was low (below the bottom line), but I could detect no water or antifreeze. I added oil, then cranked the engine for about 5 minutes, before it finally started.

Although it is running, the idle is very rough and it sounds like the engine is missing at idle and when I step on the gas. Haven't driven yet, just revved while parked.

Does anyone know what might be wrong? I was thinking about checking the plugs, could one be fouled or ruined from the heat? Or, is this more like a warped cylinder head, block, causing a loss of compression?

If the leak is fixed get a can of brake clean and clean any electrical connection that may have sprayed with anti freeze. Try to get it up to operating temperature and drive it you may have a blown head gasket.
Try minor repairs first put a pressure tester on it and run it with 3 or 4 psi on it usually a head gasket will pulse the gage. If doing it yourself try to borrow a tester at Auto Zone, Advanced or O'Riley's. Radiator shops will do a gas analysis and you can be sure before pulling a head. If pulsing the gage you are also sure.
Anyway you will loose water if you have a blown head gasket. Get the head checked for straightness and pressure tested while it is off.

Thanks for the info.

Since my post, I have discovered that water has gotten into the oil. I came back to it a couple days later and the oil level was way above the top mark and had milky/cloudy spots... I pulled the front valve cover and found moisture drops on the top of the cover and more cloudy oil. It's strange how it took a couple days to show up. I've never seen it take that long to show.

So now I know I have to pull the heads, check gaskets, etc... At least this is the single cam motor, so I have a little more room to work with.

I now have the cylinder heads off the car. The first two cylinders in front, from left to right were filled with water. The rear cylinders only had a very small amount of water, possibly just from water circulating through the engine??

The head gaskets are intact, so it appears only the front head is warped.

Does this sound right or does it sound like the rear head is bad too? Any tips on anything else I should do?

I would pay a machine shop to check the heads for straightness and have them pressure tested. I would take a flashlight and lay it flat on the block look for any cracks especially between the cylinders. This prevents a lot of problems a hairline crack can mean doing the job over again. Keeping everything clean and straight really cuts down rework.