Flat spot on 77 quadrajet when cold

[OxonCounty77]

Hi
I have just fitted the electric choke conversion that I bought from CarbJunkys as the old hot air choke was useless.
(To my 77 GMC C15 truck, 350 V8/Quadrajet)
It works brilliantly-It now starts better,I now have fast idle,& it returns to normal idle in 3 minutes.
I was hoping this would also cure the following issue,but it's still there.
The engine still cuts if I breathe on the throttle on a cold morning until the engine is warmed thru,when it then pulls/drives beautifully.The accelerator pump jets seem to be squirting fine,the throttle spindles dont seem too worn,& the engine seems in great shape having done 100k miles.It retains the standard air filter & I have replaced the hot-air trunking to the exhaust manifold.All the vac hoses look fine & the carb looks immaculate.
If you increase the revs very,very gradually the engine will rev,but press the pedal normally & it dies.As I said,after a couple of minutes warming thru,everything is perfect.
Does it sound like any adjustment/tweak would help the problem?

Best regards,Andrew. Oxfordshire,England,UK.