The Holley simply will not close if your engine is producing enough vacuum. Oiling and all the other tricks did not work on mine. Adding the Idle hole in the IAC housing only helps keep the IAC counts down since there is no venturi on the Holley like the stocker, won't help with the blades closing. Sell the Holley and get a BBK and you'll have a load of other issues...all of the aftermarket TB have issues...don't know why no one can make one the works as well as the stocker, its not rocket science to make one work properly
Here's a thread that goes into detail of what I did.
http://web.camaross.com/forums/showt...ghlight=Holley

Long story short..I took the assembly apart and wound the spring an extra turn from what is was...resulting in too stiff of a pedal, so then I added some extra spring retension holes in order to wind the spring only 1/2 turn and worked perfectly as the pics below show:

 

My professional products 58mm works great, and at half the price!!

Took it out of the box and bolted it right up, adjusted the screw and was good to go. I did have to adjust my cruise cable though. no drilling, nothing.

 

I was thinking about dising out the bucks and getting an Arizona Speed and Marine 58mm..... are there a ny known problems with thier 58's?

 

I added this extra spring to my BBK and haven't had a problem since.

If I was going to do it again i'd probably just go ported stocker. I could of swore i've seen a guy selling stocker TB's on ebay ported out to like 53.5mm or maybe 54mm. That would probably be good enough for me.

 

That's not entirely true. I have had a Holley 58mm tb for many years and no problems since the install. So, while many may have problems, I seem to have one that doesn't

IMO, the AS&M is the better of all the 58mm throttle bodies. Out of all my reading, the AS&M is the only one I don't ever recall somebody having some type of issue with.

 

The key words here being "many years". All of the new ones don't seem to close if your pulling more than 15-18in vacuum at idle..at least the 3 I have now dealt with on locals cars.

 

Exactly why I'm willing to dish out the bux and try them. I was so dissapointed with the holley. It was a very well manufactured piece, and it looked beautiful... but all it ever ended up being was engine jewelery, because it never worked properly. I may by another one... if there's a sure fix though.