My 93 Nissan Altima with ~110K miles has been idling rough lately. It drives well without any roughness. I have done the following but the problem hasn't been resolved:

1. New plugs, rotor and distributor cap (note: no new plug wires)

2. New EGR Valve

There is also a lot of oil leakage that I am seeing on the engine. I have read that a blocked PCV valve may cause the leakage and may also cause a rough idle. Hence, after days of labor, I have managed to take the PCV valve out, and found the following issues with it:

1. It had oil in it which dripped out when I held it vertical.
2. The breather separator seems very dirty.

My question are the following:

1. Is there a filter in the breather separator which needs to be replaced? Autozone tells me that 93 altima does have any. Is that correct?

2. Is there a way to clean the breather separtor without taking it off?

3. Could the IAC regulator/vale be a cause for the rough Idle? I took it off but don't see any significant carbon buildup.

Thanks for your reply.

from my experiance its probably the IACV, had a different vehicle that was having idle problems and that solved the problem entirely

Thanks pryde300zx.

I took off the IACV and cleaned it. I haven't had a chance to put it back on, but should be doing so soon. I'll post my findings later.