Do you find yourself driving a lot with the throttle barely cracked open (cruising)?
My holley needed the IFRs restricted to solve the same problem. It ran clean if I goosed it and wind down and repeat, but if I tried to cruise it would load up and foul out inside a week. Highway driving was no problem- the throttle is open enough to get into the main jets. 35 mph cruising stuck behind someone doing 34 is pig rich running on the t-slot.
