[W126 Coupe] could this be my vacuum leak?

[Shayegan, Richard]

While looking for a vacuum leak, I think I found one. It's either the
endcap on the air idle tube on the driver's side (US) bank, the tube's
fitment on the injector holder on that side that' closes to the
firewall, or the injector holder on that injector. I'll just replace the
air idle tube, endcap, and fuel injector holder and seal since those are
all cheap and that injector is super easy to remove. 

The thing that I don't get is this: if that is my leak, spraying carb
cleaner should SMOOTH out the engine, shouldn't it? Because spraying
carb cleaner there made the engine rough (as if you were spraying in the
air intake and sprayed too much). Still though, that's the only part
where spraying made a difference so unless someone says otherwise I'm
assuming that means I have a leak.

Thanks,
Richard