Well ALLDATA might not include resurfacing the head.
ALso, there are things that happen during the repair. Small hoses may break, the mechanic might be charing you for the new coolant he is going to be putting in your engine, plus new oil... and the list goes on.
If you want, you may shop around to get a better price, but 1200 for this repair does not sound unreasonable if it is a head gasket.
Try spraying some starting fluid along the intake gasket and see if the idle changes. If so, this vacuum leak is big enough to set this p0304. If this does effect the idle, I would replace the intake gasket before replacing the head gasket. Unless of coarse, there are a tremendous amount of bubbles consistently coming form the coolant in the radiator. Then My money would be the head gasket. Just be sure to have the mechanic run the correct tests before replacing the head gasket just to be sure.
THat is correct. These motors are very good but very hard to work on.
I would say with that bit of extra info that you just gave me, that the head gasket is for sure your problem.
The temp sensor very well could be bad. But in fact if the head gasket is really bad, (which it sounds like it is), then it would pump air pockets into the cooling system causing erratic temp readings. Just a thought.