SU Carbs(HiF's)- Idle woes

["Allen W." <AJWILLIA@UA1VM.UA.EDU>]

Need some advice on tuning my SU HiF4's. The were rebuilt a short time ago
but I continue to have the same problem. Can set idle @ 800rpm and runs great
for some random period of time then it drops to <500 and sometimes quits.
Seems to occur after warm-up. The car runs great otherwise- no cutout or
stumble at normal speeds.