ok thanks man. like I said I'm waiting for a new manifold. Would a week of driving lean do permanent damage to my engine??
possibly. If your knock is detonation then it will certainly damage the motor. I melted piston #3 in a mazda B series motor like that. The splatter on the connecting rod was welded to it. It was impressive...
See here:
http://www.misterfixit.com/deton.htm
You might try filling it up with some super premium gas, or just dump some octane boost in it. If you boost the octane and the noise goes away/changes it's detonation and you should probably stop driving the car, or you will damage the internals.
If you hop it all up on octane booster and the noise doesn't change, you're probably hearing the crack in the manifold and I would run it. Just be aware of the risks with a lean running motor and don't run the dog piss out of it.