my car stutters when accelerating hard but is okay under gentle acceleration?

What is your question?

Hi Hope someone can help. I have a 2002 Saab 95 Aero and have an acceleration issue. If I accelerate gently on the accelerator the car is okay, if I depress the accelerator too much the car stutters, feels like fuel starvation. I noticed today white/grey smoke today when trying to accelerate hard. I only noticed this happen once though. The previous owner hasn't driven the car much in the last few years, so I'm wondering is this a result of the car standing for long periods of time, or is it a bigger issue. There are no warning lights appear in on the dash. Please can anyone assist?