I have the same issue with my 83.5 wbx westy. When the ambient temp
rises above 26 celcius (80 Fahrenheit) The engine slowly heats up and
runs fine until I hit a stop light when it will stall at idle. It
will not restart (cranks fine) until the engine has "rested" for at
least 10 minutes. It then starts fine and runs until it reaches temp
and is allowed to idle again when the cycle repeats.  I know these
things run well in CA, AZ and Texas where temps are often  above 80
F. Any one with any wisdom to share as to what could cause this??
>

Many thanks
  Don