Ok so if the problem is your headgasket...... this means then that you could have oil and antifreeze mixing in the oil pan. Causing your rod bearings to go bad. So, before you go to all of the work of taking the head off, drain your oil and see if it has antifreeze in it. If it does chances are your bearings are ****.

 

When I bled the cooling system (after changing out pretty much the entire cooling system, including the radiator), I topped off the coolant and ran it with the cap off, revving it a couple of times, and yes, it did spray coolant a bit. Enough to get it on the engine so I had to spray it down, which is what I thought caused the CEL to come on in the first place.

 

I rechecked today for coolant coming out (with the cap off and the car cold) when revving the engine and there was none. The cap still popped off with some force when I took if off (engine cold, not running), but aside from that, no coolant escaped even when revving.