--with wild swings of aft at cruise is to possible fuel is puddling in the manifold and then being evaporated into the mixture every now and again? ultimately i would believe that the air fuel charge is falling out of suspension in a dual plane or maybe there is some reversion going on in the intake, valve not sealling all the way, etc? there is a reason port efi is the way to go to minimize variances like this.

Jerry, this is an excellent thought and one I had not considered before! The AFR at cruise is certainly very rich. The motor turns 3K at 65, and I'm not sure if fuel would drop out at that point or not. Have you seen this before?

I don't see the same effect with the AFR swing with my 3310 but it may just be that it is not quite as rich as the QFT carb at cruise.

There is also definitely reversion as well, and I often see small amounts of raw fuel if I pull a vacuum cap off one of the vacuum fittings on the throttle plate. My cam is in at 109, and I have been toying with the idea of advancing it some over the winter. That would reduce the reversion some.

I don't think it is a valve sealing issue since I have adjusted the valves many times, and have run both compression and leakdown tests, and don't see anything odd.

EFI certainly has big advantages, but it does come at quite a cost, at least to support the type of HP levels the motor should be capable of.