engine "noise" at 2000 rpm only?

[Vitalie]

Thanks guys.
I ordered the stethoscope form amazon. somebody was selling for $1.95 + $5.49 shipping. Also the harbor freight has it on sale too for 2.99.

I was messing with the engine trying to locate the sound and I decided to take that exhaust manifold metal cover off and see if it makes the same noise. well look what I found

Surprize!
   

This is cylinder #4. Cracked manifold. Not sure if this is the problem for this noise or even for my unresolved slight shiver on idle?
But definitely looks not too promising.


Frankly I don't even feel like fixing it. This is getting pricy.

What do you think about these apples?

Thanks