driving home the other day at about 50mph the Montero just turned off on me, like i was out of gas or something. i coast over to the shoulder, take next exit and stop on a service road. i pop the hood. there steam rising from upper radiator hose connection points, steam rising from coolant resevoir and generally from top of engine. coolant resevoir is also almost overflowing. i put my hand on upper radiator hose and can feel/hear a "gurgling" sound.
i wait 30 mins for her to cool down. steam goes away, coolant level in resevoir returns to normal. i try to start, and it won't. it'll turn over, but it won't actually kick on. i had a friend tow me to the nearest shop and they are looking at it now.
coincidentally, i have had a problem with my electrical system where turn signal lights would stay on if my headlights are on.
so i'm wondering if anyone thinks the two are related. here is what i am hoping: faulty ground wire somewhere caused her to shut off. as things with vehicles often do, at same time thermostat or lower hose malfunctioned.
here is what i'm not hoping: timing belt went out.

anyone experiences something similar or have an idea they'd like to share?

ps. i did have the t-belt replaced (and h20 pump, plugs, etc.) at 110k. she now has 143k.