Can anyone suggest the root cause of the following fault on my 1969 4/4?

This a 1600GT Ford crossflow with a single Weber carb, and a mechanical fuel pump, unleaded head, Shell V power fuel. Standard distributor with electronic points. Manual choke.
Car starts and runs normally initially, for maybe 10 mins. Once thoroughly warmed up though, when the engine returns to idle at say a junction, anything but the most gentle application of the accelerator causes the engine to stall. The more rapidly the accelerator is pressed, the more likely the engine stalls (with a bit of a 'whuff' sound). Gradually applying the accelerator avoids the problem. Above idle, engine response/revs is normal. In fact, on recent hot days, if the car is allowed to coast to a halt, say from 30 mph, in neutral, the engine will stall before the car actually comes to a stop. Engine idles at approx. 900 rpm when warmed up and choke is fully in.

Ignition timing and advance are correct, though engine does seem to pink a little pulling up steep hills in a high gear, on a hot day. The problem goes away in the winter, ie cold days.
Carburettor has been cleaned, and the mechanical fuel pump replaced?

Any suggestions?

Many thanks

Last edited by SCX358G; 06/08/19 07:13 PM.

Blue 4/4 1969, Green +4 1953