Reply to "Driving 5177"

I don't think low RPMs are an issue here, both Joe and I were hitting reasonably high RPMs a week ago on his car (Ron McCall swapped out my ring gear to 3.77, which I have now gotten accustomed to, so if anything I was mentally surprised to see Joe's tach going as high in each gear shifting naturally, but Joe still has a stock ring gear).  Not to mention that when I drove his, I "missed" 2 shifts due to the ZF in the 4th gate still hitting 2nd, briefly, not under continued acceleration.  It's interesting because the stick still settles to the left side of the 4th gate even in 4th (probably related to the rotation in his diagram at the "tapper pin").  But overall the shifting was so close to excellent, and I only had a couple hours at the time, and by the time we both did a country drive, it didn't make sense to break loose the turnbuckle to try to "perfect" it.  All the joints (trunion, shifter u-joints) appeared tight/solid visually watching the other go through the gears. You just learn to go all the way to the right side of the gate to hit 4th and 5th, not hard to do.  He had his resto shop follow George P's 500 HP 351C formula with this build (pretty bombproof), a couple of brief "missed" shifts hitting 4,500+ certainly wouldn't be an issue here, none close to redline.  But they're also not going to fix any fouled O2 sensor.  I definitely wouldn't have suspected any valvetrain, etc., issue a week ago, but with some new mileage since then, and I haven't seen this new issue firsthand, and I see the couple flames in his video from the passenger tailpipe, which I think was still on the fouled plugs.  Swapping out the driver's side plugs will probably continue to help, for now.  But it's not a carbureted engine and still in fairly early stages of EFI tuning (which "should" be self-learning but isn't always that simple), and neither his nor my main driving with our P-cars is in particularly "idle circuit" places, our drives are usually substantially highway.  I don't claim to be a master mechanic by any means, it's why I'm trying to add some details for the collective brain trust here, but I've had up to 2 P-cars at once, over 25+ years, I've done most projects by now, most several times over.  Normally I would agree with the spirited driving theory, but I doubt that's going to be the fix in this case.  I also doubt there's any "mechanical" issue.  FWIW.