Check for proper valve movement, particularly on cylinders 5 and 6. Also look for bent pushrods, which usually happens when the valve sticks. It's also possible you've blown a head gasket between cylinders, but the valve are much more likely to be the problem.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!