Carbrator is running rich

Gas fires need servicing sometimes to remove the natural build up of dust, fluff and carbon and it is probably this that is causing your trouble.
Service engineers will remove the radiants and vacuum the burner(s), the mixing chamber and check the gas jet(s) are clear, the gas pressure is correct and there are no leaks.

Using a vacuum creates less mess but it doesn't always get to the heart of the trouble and many fires that have been condemned as being worn out often need stronger medicine - should fluff be partially blocking the air supply to the mixing chamber the gas/air mixture will become gas-rich and the flame will create soot, sometimes lots of soot that vacuuming doesn't shift.
The careful application of a compressed air jet does tend to move lots of soot...

This is best done in the open air...

Running rich too much gas in mixture and not air this causes your problem. The black soot is carbon from the gas

Check your fuel pressure regulator it maybe bad.

This could be as simple as a hole in the exhaust under the cabin area. I would also check that all cylinders are firing properly. They can do a fuel pressure test to make sure there is nothing wrong in the line as well.

It could be a clogged fuel filter or you could have a old gas coated inside the carbrator. Seafoam will fix that up in a hurry. Don't be supprised if it blows smoke its cleaning all the junk bout of your carbrator. I would start with the simpelist things first. Fuel filter Check your carbrator Throttle adjustment Fuel pump relay Defiantly get a Haynes manual it will trouble shoot you through your problem.

Check your carbs and air filters

If your check engine light is on when the car is running, then that means there is probably a trouble code stored in your vehicles computer. With a code reader, you can find out what the code is. That will direct you to the problem. You can post your code here and we will tell you what it means.
Regarding the 'gas' smell, first check to see if your car is running 'rich'. You can rub your finger inside the tailpipe and see if there is a lot of black soot there, which would indicate its running too rich (too high of a fuel to air mixture). If this is inconclusive to you, remove the spark plugs and check if they are with black soot on them where the pin is. This will tell you how the engine is running in terms of fuel mixture. If they are black, then you have found the problem (fuel injection problem or Oxygen sensor, most likely). The trouble code might also point to this. Other than that, sometimes an exhaust leak can cause fumes to leak up into the car when running. My car had the gas smell problem and it was both a hole in the exhaust under the car and an overly rich fuel mixture. I had black soot inside the tailpipe and black sooty spark plugs and the final problem ended up being a bad oxygen sensor (located on the intake manifold), that was sending an improper signal to the vehicle's computer, thus the reason for the problem.

burning rich. Add SEAFOAM to your tank(at part stores everywhere) to a tank of Premium gas, and add every 3000 miles to fuel. this will help the carbon and running rich problem.

Is this a recent development? Or has it always left that smell? I had an older Sporty, that I ran too rich for years, it left lots of black soot on the inside of the exhaust tips, and a very pungent exhaust smell on your person. When I went down a couple jet sizes, it got much nicer, and ran a little better as well.

It sounds like you have an issue with something in your air/fuel mixture electronics. This could be something in your throttle body, mas air flow sensor, or even an oxygen sensor. When your car is idling the air/fuel mixture is acceptable for the engine to run. When you press on the gas either too much gas is dumped in the engine or too little. If you look at your exhaust pipe you may notice a heavy built up of black soot. This would indicate that your vehicle is running extremely rich (too much gas), if your exhaust is very white then your vehicle is running lean (too little gas). The smell of the exhaust can also tell you something about how the engine is running. If it smells sweet it is running rich. I hope this helps and please don't forget to rate me.