my car was bought 4 month ago 1994 c280 104 engine. It stalls on hold ups

What is your question?

it hardly starts in the morning. the exhaust smells like roasted oil. we have changed air flow meter temperature sensor actuator and still same.I want to change the exhaust train since the catalyst is broken inside. but ive spent heavily. when it wants to start it drops its rev and goes off. when you press the trottle pedal you hear it sucking air and the car goes off. Please what do i do.The mechanics seem not to know to do