i have had a problem with my idle Vf's and lean idle, so i decided to revert things back to stock to try and fix it. I put the narrowband O2 sensor back in the turbo elbow, put my wideband in a separate bung further downstream, undid the wideband emulation. started her up, no change. started pulling out the intake it see if the accordion hose had a crack, and thats then i discovered a decent sized crack in the plastic at the top of my filter. replaced the filter, and things got a tiny bit better, but the idle a/f was still high 15s into the 16s, forgot to check the Vf. swapped in my spare afm electronics, started her up again (by the way, all of this was done with the piggyback bypassed), and finally normal Vf's, BUT idle a/f ratios were still high, and though the idle sounded smooth, there was like an intermittent burbling in the exhaust. i played with the fuel pressure (reduced from 40 w/ vaccum to 35) and adjusted the idle. as of now, my idle Vf's are steady at 2.20, idle a/f ratio hovers between 15.3-15.5, but my idle is now 950rpms, still have the burbling in the exhaust, and when i take my foot off the gas, theres like a long lean dwell (goes lean, rpm's drop, then comes back up). coinciding with that, vacuum goes to like 18, and immidiately returns to 22 when everything else normalizes. I put the piggyback back in the mix, and noticed the edis doesnt always activate when i take my foot off the gas. i'm pretty stumped. im not sure if it is a vacuum leak, i havent put that many miles on the car since the last time i tested. oh, i also did the carb cleaner test for leaks and nothing came up. could it be an exhaust leak? any other ideas/suggestions?