Carb question - fix or replace??

[qslim]

So I just realised Im running on two cylinders under about 3500 rpm. Unless there is a decent amount of vacuum, I have no fuel. I took the carbs off and did an abreviated cleaning; sprayed all the passages, cleaned the jets, got all the varnish out from the guy I bought it off of, but the result is still the same.
I'm looking on bikebandit for a rebuild kit, and I see these Mikuni carbs available in varous sizes for around $100 each or so. So I don't know...
First off, does anything pop in to anyones mind as far as what the deal is with my fuel problem, and second, has anyone put these Mikunis on their bike?

[gspaul]

Maybe check the simple things first, is the petcock flowing enough fuel, could be faulty?
Is your idle mix dialed in correctly?
Have inspected the diaphragm's in the top of the carb's?
Have they been synced?

[qslim]

Yeah, the petcock is good, fills the bowls right up. The mix screws have no effect on anything on carbs 1 and 2 at idle. The sliders are free in their bores, and the diaphrams are good. I originally set out to correct this problem by syncing the carbs, and in the process found there is no idle fuel delivery on 1 and 2. When the airbox is off and you hold your hand to block the first two carbs, fuel starts flowing and the idle creeps up. When its free to breathe, it drops back down. I figure there really isn't a point in matching the carbs if two arent even delivering any fuel.

[gspaul]

It sound's like some of the passage way in the idle circuit may be blocked.
Or there leaking vacumn some where.