rough idling

I took my 2001 LS to my mechanic yesterday because it was occasionally misfiring (on #3) and he replaced all the plugs. I took it out and really stomped on it and it seems to have taken care of the misfiring, but it still idles pretty rough when stopped and in gear--at red lights. My boyfriend had been suspecting the oxygen sensors, but my mechanic thought plugs or coils. Does anyone have any other ideas before I call him back next week?

It's very common on the 2001 to have leaky valve cover gaskets and plug well seals that will leak oil into the plug wells, causing the coils to arc to the head and eventually fail.

With the rough idle and prior misfire code, I think your mechanic is probably correct.

If the oxygen sensors are bad enough to cause rough idling, they'd be throwing codes as well. Of course if you let a misfire go long enough, it could eventually destroy the oxygen sensors and catalytic converters.

-Rod