I understand that if an engine idle "lopes" or idles high and low rapidly, and backfires from time to time that the problem is EGR, am I right?

 

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What year/engine/fuel system?

 

a 305 TPI

 

It could be a leaking EGR. It could also be a different vacuum leak, IAC, PCV valve, throttle body deposits, and even an ignition (failing cap/rotor) problem. Unfortunately, the EGR is the most difficult to access on your engine.