Envoy is "chugging" and smells like gas

My wife's 2002 Envoy is chugging and smells like gas really bad. It has done it a handful of times in the past couple of weeks. Some days it runs great and other days she says it chuggs (even more so when it is at a complete stop). When I drove it, the smell was overwhelming. Any ideas on what it might be?

A misfire can cause this I assume that is what chugging means, a full scan is in order here to look for misfire codes and possible pending codes.

The smell may be caused by a vapor or liquid leak.
evap test needed here which checks for a leak from hole.