How do the plugs look? Black - gas fouled?
When Idling cold, does the idle improve if you open the choke slightly - too rich, maybe choke pull-off malfunction?
Does the idle improve if you choke the carb more or hold a rag over the throat - too lean? Does stepping on the brake make a difference - possible vacuum leak from the brake booster. Hope this helps.

Happy Motoring,
Mark

__________________
DrDKW