I have a 1997 Monte Carlo LS recently I keep getting the small faint smell of gas coming from the engine but when I look I see no leaks. I can also hear a small knock in the engine not loud and rough but still enough to hear and feel it. I also sometimes put the gas down on it and it doesn't want to take off but then kicks in like nothing happened.
Anything on this subject will be a big help thanks.

. Replace the Ignition Control Module (ICM). It sounds like it is failing and allowing unburned gas to build-up. Incomplete combustion can later ignite, blowing the exhaust system off the car. I would also replace the coil packs and plug wires, while you are at it.

. Change the spark plugs (ACDelco only). You may need to use the next colder plug--this often takes care of engine knock in warmer weather.

I would be surprised if this didn't solve your problem.

Thank you :)