Stumped (intermitant misfire issue)

[pontiac nino]

rotten egg smell=clogged cat, also might of fecked up you're O2's (possiblity)

[GhostRunner]

Update:

Got the car back, everything works as it did... Problem was with the new wires I put on, apparantly two of them (2nd and 4th cylinder wires) were defective. Cat's fine, O2s are fine, MAF and all those other annoying sensors checked out ok, or so the dealership said. Total bill was $149 for ignition system diagnostic & Cat diagnostic. Guess it's worth it for piece of mind that everything else is okay. Got advised that my original problem might have been the super clogged K&N, which I'm cleaning right now, got a Fram filter on it in the meantime. Funny that 3k ago the filter was completely clean, now it's caked with oily dirt almost across its entire surface.

Now to see if my tune up before all this and a clean air filter will help my original problem.

Thanks for all your help guys. I appreciate it a lot.

[Paul Ford]

Ive got a 97 camaro that was having the same problem of throwing the code " 0300 Random Multiple misfire" at any high rpm or heavy engine load. I recently found out my cat was clogged, and decided to gut it. Now my SES light is on but only for the non functional cat, i have yet to get the SES light for a random misfire since the cat. I'd be willing to bet youve got a clogged cat. try tapping it with a hammer to see if it rattles at all