I think you are mimicing what I tried and if it runs OK warm I would not worry about it . I would look at the air slide and temp sensor like you are and maybe spray carb cleaner or propane to see if you have an intake gasket or FI injector gasket leak. Mine does not idle the best unless the air inlet sensor is disconnected that I think causes it to run rich. Even when I adjust the ECU full rich I can not get to idle as well as with the sensor removed. This sensor was diconnected when I got the car alos. I have an O2 Halmeter in line so I see it go richer with the knob adjustemt. My theory is the injector timing is changing also with the air inlet temp sensor is disconneted. I defer to Phil or George on what you should do or if it a real problem (chasing Djet ghosts like me). Here is the recap of my toils. I would try the retourqe but I did 5+ head gasket changes and a complete rebuilt head change with little help.

Greg Bodner
1970 1800E

Here is what I have done since the fault.

Noted after initial rebuild and startup (30 min cam break-in, 1 hour
drive. ) #1 header pipe was not discolored and #1 plug not brown or
looks un used. . #1 temp = <200 deg F. #2,3,4 = 600 deg F or
greater. Temp does not increase from idle or more that 50 degs upon
3-5k revs .

Rebuild included. block baked and cleaned, Rebored .030, New Mahle
ceramic and dry filmed pistons, balanced clutch/flywheel, balanced
crank and rods, crank polished/turned for .010 under new rod and main
bearings, new cam ISKY VV61, new cam bearings, new lifters, new ISKY
chrome moly push rods, new oil pump, new starter, rebuilt
distributor, new water pump, new fiber timing gear, 4 new injectors,
ceramic coated intake manifold, new aux air slide, new temp sensor,
new thermostat, Stage 1 header.

Retourqed head, readjusted valves, change plugs, swapped in old plug
wire, swapped injector. Flow checked injectors and checked spray,
Checked spark with inline spark gap checker. Failed same.

Removed head and replaced gasket. Adjusted valves. Did leakdown
<10%, Did compression 160,165,165,160. Retourqued head 170,165,
170, 170. Reversed fuel flow on fuel rail to give #1 first shot at
fuel from pump, cranked up fuel pressure 28 psi to 40, Changed
distributor back to point version one, changed cap, rotor, swapped #2
and #1 wires. Failed same. Did night time spark arc check. No
sparks noted. Removed FAN BELT to see if fan was causing #1 to be
low (closest to fan) . Did not help.

Installed original exhaust manifold (took off header) and inspected
intake manifold for blockage. None found. Checked header at the same
time but #1 tube AOK. Failed same.

Rang out all injection lines ( open, short to gnd etc.) back to ECU
AOK. Replaced FI ECU and failed same.

Removed head and had it decked and magnafluxed. Reinstalled with
new gasket, header back on and failed same. Removed and inspected
timing gear AOK, inspected relation of cam to distributor and valve
train, AOK. Replaced cam with a new one and back to stock D-Grind.
Failed same.

Bought new rebuilt head. Lapped in valves and had sensors installed.
Installed with new gasket. Did compression check, 165,160,160,165
Failed same. Retorqued head. 180,175,172,180 compression.
Readjusted valves. Failed same, Swapped distributor to rebuilt one
with Perlux pointless module, swapped cap, rotor, #1 plug. reswapped
#1 and #4 injector. Swapped ignition coil. Failed same.

Drained coolant and ran engine for a few minutes to see if head leak
that leakdown did not show. . Still no temp #1. Did leakdown with new
head this time ran pistons up and down bore. Had 78/80 leadown or
almost none.

Can pull injector connector and or spark plug to #1 and engine
stammers/misses as with any other cylinder. Some spark and some fuel
but no power.

Each time

Timing was adjusted each time and played with . 15 btdc +/- 10
tried. Verified timing and cap wire placement , Sprayed carb
cleaner and propane to check for intake leaks. Lots of new plugs and
some stuff I am forgetting.