i'm not sure but my ex had a mk2 which kept stalling at junctions. the choke flap was sticking in the carb and the base gasket had gone (they're quite hard to get hold of apparently) if its this your best taking the carb off and stripping and rebuilding it with new gaskets. when my mk1 cabby was doing it it was when the automatic choke was knocking itself off and there wasnt enough warm air getting to the carb. if its a carb look under the bonnet and check if theres a pipe that looks like foil coming off the exhaust heat shield to the carb. if there sint one. put one on. they dont cost much. - Try this one first, its the most cost and time effective hope this helps, sorry i've been a bit vage!
I'd checke all the Usual service stuff.. filters (air and fuel) dizzy cap/ rotor arm/ leads. Check Water and oils (head gasket)... Does the fuel pump sound noisy? Also check inlets and gaskets too...