I think I found it guys.  Headed out for another road test, but it all looks and feels very promising.  Any last guesses on what is was?

Just an update from my previous post from earlier tonight:  I pulled the carb back off after things cooled to look over that Demon Idle-Eze circuit and I noticed a film of oil in the intake manifold.  This is the first time I noticed it and I have had the carb off half a dozen times in the last week. (I always glance down the manifold just to be sure I didn’t drop anything inside).  The oil is in both planes of the manifold.  Not sure if a bad PCV valve would cause this, because with all the idling lately the engine has been in a high vacuum state for extended periods or if it is drawing oil from elsewhere.  As I stated on Saturday the plugs are OK, definitely not oil fouled.  Perhaps my original thought of a vacuum leak is correct? 

That actually makes a lot of sense GerryP.  I don’t know if I should have done this or not, but when I built the engine I put heat riser block-offs in (something I always have done on Fords).  So any hot exhaust gasses should not be able to pass through the intake.  I don’t know about any restrictions in the exhaust, but I can sure respect your opinion.  I have the FPA tri-y’s going into 2.5” exhaust through dual 40 series Flows.  Is there a chance I mismatched something on the head gaskets related to coolant passages?  I would have thought any issues would have popped up before now.  When the motor was fresh, we used to drive the car to a lot of shows with no issues.

jayb- the fuel gauge at the reg reads 7 PSI and it reads this right up to the time that the engine shuts off.  No fuel pours from the bowl vents at all.  No vac advance at all...all mechanical in the dizzy.  The coil swap is next on the list.  I may have the old point distributor laying around, so I can try that as well.

427LX, I thought the pressures seemed low as well compared to my small blocks.  I have an ancient compression tester with the rubber boot that you have to hold in the plug hole while you crank.  I usually crank it over about three compression cycles to get the reading, but I am never confident that I am getting a perfect seal and thus an accurate reading.  What numbers would you expect?  I am running L-2303NF Sealed Power pistons with the CJ heads on a stock crank setup.

Folks this is my first post which is actually to ask for advice on how to diagnose and proceed with an issue I am having.  I have been around SBF's a lot, but this is only my second FE.  I have a few old Ford muscle cars in my collection, but the one in question today embarrassed me today as it let me down right in front of a car show!

I have a 67 Fairlane with a 428 (I did this one for my wife).  I built the engine about 6 years ago (but only 4000 miles).  It is a .030 over 428 with CJ heads, a CC XE 274 hydraulic flat tappet, roller valvetrain , headers, and a Demon carb.  Nothing radial, but it has been a good runner on the street for sure.  Lately the engine will shut off when coming to a stop and will not start (but it will crank over just fine) although it will backfire while attempting to start.  The H2O gauge reads about 190 deg when this happens; so not extremely hot.  I am positive it is not a vapor lock or percolation issue as there is an electric fuel pump on a bypass regulator system.  I can see fuel in the bowls via the sight gauge glass and everything looks great there.  No fuel is dripping from the boosters and the carb and fuel lines are NOT hot at all.  The car pulls hard (rubber coming out of 3rd gear) when cool, but give it about six or seven miles and it feels like I am driving a model A Ford. 
Today, I had the car in the shop to check timing, etc.  While idling at 800 RPM (after about 8 to 10 minutes) the engine started faltering, stumbling, and it shut itself off within a minute of doing this.  I tried this again after it cooled and with a vac gauge and I read about 10 in-Hg and right before it stalled out it was fluctuating between 8 to 10 in-Hg.  The ignition does not seem at fault (about 12 deg initial) on a Pertronix billet distributor and a remote mounted coil.  I yanked the Motorcraft plugs and they appear to show a lean condition and while they were out I checked compression and all cylinders were around 115 PSI with the carb removed.  Also, since the carb was already off I quickly swapped on a Holley 750 DP from my Mustang and it gave the exact same results as the previous combo (which would seem to rule out any carb issues).  This issue is very repeatable as you can let it cool just a few degrees  and everything is good, but it always quickly returns with heat.
So, I am leaning towards a vac leak caused from a poor gasket seal or an intake crack (Edelbrock Performer manifold) that shows itself with heat, but I would rather obtain some advice or another opinion before I dig into this; since as you know this is more involved on an FE than other Fords like I am used to.  Perhaps with your experience you have ran into something like this before?

Sorry for the long post...I hope my future posts are less needy.  I like to figure things out for myself so that I can learn from it, but this one has me stumped.