new thermostat 3 months ago? that coulda been the burp; i only partially burped my 01 v6 mustang and the heat came and went for years after that
on a real note, i had a friend that has the 5.4l 3v in a 2005 f250 super duty right. and he noted that his truck would over heat sometimes. well he was under the impression that if the check engine light didn't come on when this occured, then there wasn't a problem..? (he doesn't know what oil goes in his truck) so he let this continue until the check engine light
did come on. And even then, he'd just turn the truck off and then right back on, and the CEL would go out, so he would drive some more!! fortunately it didn't blink, however, when he finally decided to tell me about all this, i told him he was a nut for letting it go that far, and that the check engine light wouldn't come on for an overheating condition until the motor began to misfire! well, it turns out, i was wrong. if you over heat his truck (and i'm going to assume our cars) hard enough, for long enough, you will get a wild p2*** something code (i cannot remember the code #s; typical scanner will say manufacturer's code anyway) but it was the only code, and the code indicated that the computer had realized he didn't care that the meter said HOT, so it began to not fire coils, so that heat was not generated, and cool air was pumped through, in an effort to keep the motor from getting to hot.
this dummy resistant process seemed to have saved his truck; i put a new thermostat in, and everything was ok.. and that was 5k miles ago so.. i'd say you can likely drive the piss out of it while it's over heating, and it will likely not die.. ??
i'm a laid-off ford mechanic, and i've pushed cars really hard just to see if they would die competely (hey we told the lady it needs a new motor anyway) and you would be surprised and what they will take. my friend with the f250 ran his 3v a whoolllllee lot hotter than i woulda, including flipping the key off and right back on, cause it was running funny (intentional misfire cooling mode) and the CEL was on, and then kept on driving it.. and she took it.
just my $.02