If a catalytic converter does become clogged up it will reduce the airflow from the engine to the exhaust and cause engine stalling problems as well as loss of engine power, hesitation and much more.
An engine needs to be able to properly exhaust and if the engine cannot exhaust properly then engine problems can occur.
If your engine is cutting off and stalling a lot then I would first check the ignition system though such as the spark plugs, spark plug wires, ignition coils, ignition control module etc.
If it isn't that then check to make sure your engine is getting enough fuel and that your fuel filter is not clogged or your fuel injectors aren't dirty.
After checking all that then I would go for replacing the catalytic converter but would wait to do that last as catalytic converters are expensive and expensive to replace.
But yes a catalytic converter can cause a cars engine to lose power and stall.