that guide is probably busted if it sounds that bad....
are you talking about a single cam or a dual cam?
If the tensioner on the single cam goes bad, it'll still run for a while. It'll just slap the chain around for a while until it finally decides to jump teeth.
The dual cam is a little less likely to jump teeth, but it happens.
Take the valve cover off and take off that upper guide. It isn't needed.
If your noise went away, then you were just over exaggerating the noise.
If it didn't go away, then you probably have a bad tensioner.
Most of the time you can take the tensioner off and blast it with wd40 (or the like) and it will break up the gunk and free it up.
good luck