Sounds like your running really rich. Is your exhaust really black?

Are your catalytic converters shot?

Have you run any diagnostics yet?

 

Well, I'd check to see if any of the cylinders wasn't firing, leaving a bunch of unburnt fuel mix to burn up in the cats, thus the gas smell/black smoke.

You should probably go to a good Z mechanic and have them go through a complete mechanical check up for what needs to be done now, what should be done soon, and what could be done for preventative maintenance.

Good luck.