Engine light flashes and car runs rough also smells like gas and sulfer

What is your question?

So I am working on a 2004 Pontiac grand prix gtp for a friend and I've replaced plugs wires because the engine is misfiring. The car has 150K miles and nothings been changed so I figured ok just needs plugs and wires. Now I have been doing research for the last few days now and everything I'm seeing is coming back and pointing at either a bad coil or a bad icm. I'm also going to change the fuel filter just in case if its not getting enough gas. I have ran codes and it comes up as P0300 Random cylinder misfire. when the car is running for a few min the engine light flashes. when it gets warm the car dies and wont start back up till cooled off or if put in neutral with gas peddle pressed half way.

What makes this problem better or worse?

its worse when engine is hot

How long has your 2004 Pontiac Grand Prix had this problem?

1 week