Got me stumped

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Yeah, I used new torque-to-yield headbolts. The replacement heads were exchange ones from the machine shop, which performed perfectly all last summer and this one.
I had overheated the car badly last summer which caused one valve guide to drop far enough to hold a valve open; upon disassembly I found several other guides almost to the same point and thus replaced both heads. My initial check before starting that procedure indicated 150 psi on all cyls except one which had zero. The dead cyl currently has 150 and I didn't bother to check any others--all I know is I pull the plugwire off and the rpms don't change. I, too, found the appearance of the plugs to be "not what I expected." I run 10% ethanol (gasohol) in it most of the time, but this last time I put premium in it just grasping for clues what might change the way it was running. This might account for the coating on plugs(?) which are otherwise fairly new. I'm usually a little leery of buying premium in any case since it doesn't sell anywhere near as quickly as the other so you don't know how old it is... plus the prices now probably make it so nobody buys it at all.

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