I have a similar surging problem after installing my FMIC. I'm curious to follow this thread and perhaps lend a hand since I have the same problem. My surging seems worse when I am at very light throttle, pulling about 16-20 inches of vacuum. Once I am heavy enough on the throttle that I reach 10 inches of vacuum, the surging goes away.
I've logged during this surging and I have not found any obvious problems, fuel trims are working properly in CL and AFR is switching just above and below 14.7. Timing is steady.
I have the stock BOV, which leaks a LOT of air back into the inlet hose during idle and very high vacuum situations.
I have some other fueling issues I need to get fully sorted before I can go much further on my car. But if I can help, let me know.