Bad news I think. I talked to my parts guy and he too suggested that I check the valves (should have listened to you long ago Colin). As a quick check, he told me to hold a napkin up to the exhaust and see if it ever gets pulled against the outlet and, sure enough, the paper pulses back-and-forth. Very upsetting. I want to use a compression meter to make a definite diagnosis, but how do I know if compression in a cylinder is low that it's the valve and not a bad ring? If it is the valves, is there a way to check if it's just sticking, out of adjustment (I haven't read that far in Haynes yet - does it give a good procedure?), or completely shot? I'll save my dreaded questions about estimated cost of a valve job for later (after I've bought some Scotch)...