being told by who? Anyway, seriously, I'd check the oil to make sure. Even if the HG is ok, a warped head sounds like the symptoms you described (running like crap, sputtering, stalling, etc)
Just one of my friends. Not a professional or anything.
BTW, I was just reading the symptoms of a blown HG, and it said a whistling sound may be heard. Any chance that's the "squeal" I was talking about when we were puttering around the parking lot?