Runs rough, intermittently turns off, smell of gas in cabin
The fuel pressure regulator may have failed.
Locate the regulator and remove the vacuum hose.
If gas leaks out of this connection, the regulator requires replacement.
Good idea above. If FPR looks ok, next step is probably to ask your mechanic if a fuel trim test would be helpful. That test checks for overly rich/lean engine operation, and usually doesn’t take a lot of shop time to do, so isn’t overly expensive. The mechanic should also check for any stored diagnostic codes of course. I’m guessing you have an engine misfire.
Really need to get the diagnostic check. My riviera had a Crt screen and I coukd go into diagnostics at will to check codes and sensors. I was getting maybe 12 mpg. The computer showed a lazy or non functioning O2 sensor. Changed that and took it fir a drive and instant climb to 25 mpg. Doesn’t have to be something complicated but if you smell gas for sure look for leaks.