Hi, Thanks for your input. The Thermoquad number is 9009 and the top casting 2141. My idle screws are 1 1/2 turns out for an AFR of 13.5. Just to check on terminology, the IFR is what the manual calls the Low Speed Jet?
Interesting point that you are calling the idle circuit the cruise circuit? I had been trying wires in the high speed circuit vents/bleeds with some changes but not fixing my issue - maybe I need to spend time on the Idle side, it could be supplying too much fuel at light cruise causing my rich mixture?
Having just said the above I have found that one of the Idle Air Bypass brass inserts has been ""peened"" over during the re-manufacture process - still a passage bit much smaller than the other side. This could lead to a rich idle circuit on one side?

Another issue on the varying AFR with speed; when I am at cruise and accelerate moderately (not on the secondaries)the AFR reduces by about the same at any speed (about 2.0) so if the cruise AFR is on the rich side I get poor accel from an over rich condition, similarly poor accel if the mixture is lean. This is easily noticed when driving and the other reason I am trying to get a consistent AFR.

Thanks again for your input and the first thing I need to do is somehow fix the one idle air bypass and see where that takes me.