I was recently cleaning my throttle body when I noticed something odd. There's a small hole, about the size of the tip of a ball point pen, just behind the butterfly plate, near the bottom. The hole goes all the way through the throttle body. Should I be concerned about this and fill the hole with something, or just let it be?

 

I have this too... I don't think it goes all the way through the bottom of the TB does it? Mine is a 96 GLE too... I just noticed it last time I cleaned the TB out (2 weeks ago)...

 

this is normal. Its there on purpose. You dont really think it just made a really small perfectly round hole in the TB just from putting miles on your car do u?
Its there to create a vaccum in the trottle body to suck the air into the TB chamber...