I spoke with the mechanic about this situation and this is exactly how a shop can take a bath. They quote a price of $300. to do the tuneup and they have to eat another 10 hours of struggling with the plugs............with the presumption that they don't have to remove the head. If so, it turns into the biggest loser of the month.

What customer would accept a bill of $1500. for a tuneup? Nobody would unless it was quoted in advance by a shop who didn't get suckered into it without looking carefully (which none of them would do).