CIS Help -- Losing Power at High Revs/Altitude

[echrisconnor]

I started this question in another post, but thought I'd give it a topic of it's own.

I've been working through timing and mixture issues and have encoutnered a new problem. Yesterday when driving at high altitude, the car started to cut out/hesitate at high revs under wide open throttle. Upon returning to lower altitude this problem went away. So, my thought is that it's a mixture thing, but I've never encountered this before. In general though even at normal altitude, I feel like the car loses umph at high revs, where normally I'd expect more power.

Is this a potential symptom of being too rich? The car runs great at partial throttle, with no hesitation, burbling or backfiring.

The car is a Carrera 3.0 with 964 cams, SSIs and a sport exhaust. Points and dwell are good. Timing is advancing out to 35deg at 6000. Control pressures should be good as well. Mixture, however, is just set by the lift/lower the metering plate and has not been done yet with a tester.