Possibly.

 

After parking Betsey (my 97 S Blazer 2X4) due to the multiple random misfire coupled with a completely cooked Catalytic converter, I have revisited and solved the problem.

Due to the melted parts of the Cat posing a risk of plugging the exhaust, the first step was to replace it. Fresh tune up again, plugs (AC) Wires and Cap & Rotor. Replaced EGR. Replace several rubber vacume grommets to ensure no vacume leaks.

Remaining Symptoms: (Beside P0300 code - Multiple Random Misfire)
- Starts and runs fine until ~5 Minutes from start.
- Loads up and misfires at idle, and clears after ~1800RPM, sputtering to that level.
- Gas smell from the uneven exahust, and black exhaust pipe.

Put a pressure gague on the fuel pressure regulator and it was running over the recommended pressure at idle, and upon shutdown, it did not retain pressure.

Replaced the Fuel Pressure Regulator (with the help of a friend) and she now starts and runs like a top. Finally, going to get her smogged (CA resident) and re-registered.

Hoefully this post will be useful to someone like me who was completely stumped by this condition and code.

Cheers!