Unstable with missfire

A month back I took my car in to get a SMOG check done on it (gotta love California! :mad:) Anyhow, I failed miserably and eventually found out I had an exhaust leak where the header meets the Y pipe on (before the O2 sensor) So I ended up fixing that an my miles per gallon went from 11mpg to 19mpg and everything seem to run better.

Well I took it back in for the retest today and I was told the engine was unstable and it was misfiring, therefore since he couldn’t keep a steady speed because it kept "surging" he couldn't complete the test and I failed AGAIN!!

Any suggestions on what would cause the vehicle to surge/misfire or whatever else you might want to call it!!!

If your curious about the previous SMOG test check my old thread http://www.camaroz28.com/forums/showthread.php?t=624321

All comments and or suggestions are greatly appreciated!

Is it possible you fouled the plugs when it was running rich?

+1 on Inj's thought.

As a State Inspector here, I would like to think that the rich condition (depending on how long it ran that way) could have caused a multitude of issues downstream. IAT/EGR/PCV/HO2S systems all could have more than a "little buildup" on them that would cause the PCM to "adjust" the conditions for "optimum efficency."

Do the simple stuff as far as cleaning out the fuel system with something like the Seafoam or Techron stuff. There is a nice method on the back of the Seafoam treatment that instructs on actually going thru a vacuum line or brake booster as to get a more thorough cleaning. Whatever the hell you take that for.

Running a car "too rich" is one of those "short term gains" that you can almost always pay more for later.

Remember KISS and don't be afraid to delve into it...

Can't be much to fix.

Good luck and LUK,
Ivan

Plugs are probably a good possiblitly. It seems like a huge pain to change the plugs even with edelbrok headers and not the stock ones. Is going from below any easier or should I just remove the headers, buy a new gasket, and change the plugs?

well i changed the plugs (after 4 hours) and also realized i had a wired that had beed touching the headers and pretty much melted in half......That explains the surging.........I completed it and took it in and finally passed SMOG.....after almost 2 damn years im finally back on the road with it (legally that is).....thanks to all for the suggestions over that time, especially injuneer!!