Just thought I'd post a tad of useful information here that I found from the Haynes manual. It describes some problems people may have been having with a low rpm stumble!

Book #24017, Chapter 6 Section 5 - EGR System.
1. The system meteres exhaust gases into the engine induction system trhough passages cast into the intake manifold. From there the exhaust gases pass into the fuel/air mixture for the purpose of lowering combustion temperatures, therebye reducing the amount of oxides of nitrogen formed (NOx).
2. The amount of xhaust gas admitted is regulated bya vacuum or backpressure controlled (EGR) valve in respone to the engine operating conditions. The EGR valve is under the control of the EGR vacuum control solenoid valve which in turn is under the control of the ECM/PCM. The vacuum signal to the EGR valve is controlled by varying the duty cycle (on-time) of the solenoid valve. THe dutycycle is calculated by the computer using information from the ECT, MAF, VSS, and IAT sensors. Problems with the EGR control circuit or the EGR valve will set codes 27 or 32.
3. Common engine problems associated with the EGR system are rough idling or stalling at idlem rough engine performance during LIGHT throttle application and stalling during deceleration.

I would think that this passage/valve etc get covered by carbon over time on our aging camaros'. this is likely a common problem... The manual gives a checking procedure for each comonent (EGR valve, EGR Vaccume Soloenoid); and also instructions on cleaning the EGR valve (remove, inspect, clean with drill bit).

I know a lot of people have the Haynes manual but it was in a part of the book i've skimmed over in the past because it seemed boring. This time i was reading up on how to use my new multimeter and to my surprise came across this section

After scanning the board for solutions to the low rpm stumble it makes sense that a faulty MAP sensor or new fuel injectors, bad MAF or VSS were related to a low RPM stumble... I'm gona check my EGR the next time i get some time to =]

 

sounds like some good info, thanks. typically a low rpm stumble is associated with the optispark taking a dump, whcih is all to common it seems.

 

I should also note that my NOx levels (My car just passed emissions 2 weeks ago) were just BARELY at the verge of failing. I need to pull out the slip to verify this but I belive it was very close. This falls in line with what #1 said.