General AFR Guidance (Holley Tuning)

Aaron65 said
You can test your idle circuit by temporarily putting small wires in the idle air bleeds, which will richen your transition circuit. ***Make sure you secure the wire so it doesn't get sucked into the carb*** If it runs better, then you know you need a richer idle circuit.

Wires are a good way test.

If it's just off idle that you have your problem, a new power valve probably won't help, nor will a different pump cam (this is only from my experience: your results may vary). :)

Your experience is backed by physics. See post here for link to video. The main jets are usually much larger than the IFRs so have little effect on flow. This assumes a submerged IFR. A good modification to start with if its high. See http://racingfuelsystems.myfunforum.org/viewtopic.php?f=25&t=1338

mopowers said
I do think the IFR needs to be larger in order to richen the transition circuit a bit. That would mean the idle mixture screws would need to be tightened as well, right? I'm already only at 3/4 turn out from bottomed out on all four idle mixture screws.

Not enough info yet to decide whether to change the IFR or the IAB. Yes, with 4 corner idle the fine trim screws might only be 3/4 out.
First you should make sure (idle circuit) needs to be richer by doing the super slow opening test I described earlier. If it doesn't need it, then its just extra fuel washing things down..
If it does need to be richer in some of the range, you will then have to experiment with IAB and IFR combinations. Does it need to be just richer or also carry higher into the rpm range? Changing the combo will effect both richness and when it stops flowing.

Keep noting the turns out of the idle mix screws. It's another clue as to what is going on with each change.