1988 Porsche 911 Loss of power

1988 Porsche 911 6 cyl Manual

This morning on my way to work my car hesitated then loss power and stopped. I waited 5 minutes and it started back up. I pressed the gas and noticed a surge of power then a little hesitation but it kept running at idle speed.
I drove the car gingerly to a mechanic shop and they have not been able to give a reason for it stopping.

Any ideas?

Thanks - Gary