Idle drop by 500 rpm?

It's 12 years old. Seen some dragging, and a few years of street use, daily, I'd hate to think i killed the Throttle shafts...what's odd is the Darn thing, after following RustyRatRod and Mattax instructions, to a t, she fired up and idled at 650, then dropped to 450 in gear.. then I tweaked the idle mix screws out, that raised the idle... checked w/ a light, timing was to advanced, so I retarded the timing. At some point, I gave it a little gas, and got a pop outta the primaries. SOB never idled since... Thanks Kim, hope all is well, Chuck

I'm no holley expert, but a pop can break some parts. Mostly the power valve I'm told.
Might be worth a look-see. Lots of instructions in how and where and what to look for on google.
Supposedly holley "fixed" the power valves to not fail after a pop, but if the pop preceeded your issues... Well, there it is.