I recently changed spark plugs, wires, dist cap and rotor (with little noticable effect on rough running) in my 87 K5 (350 auto EFI). The back two plugs on the pass side were wet with engine oil, and the last one was crusted pretty bad. All the rest were surprisingly clean, no carbon, nothing. Could this be a valve problem? How much would repairs cost? I don't know if this matters, but six years ago, before I owned it, radiator trouble caused a severe overheating and the head gasket blew. It was replaced, and I assume the head was machined, too. Time spent fishing is not deducted from one's life span.