OK, folks, help me out.
P5, 178K miles, recently (as of last week) developed a rough idle AND it takes longer to crank now.
EGR replaced at 161K miles. IAC inspected at 161K miles and was clean. Spark plugs changed at 174K. Wires replaced about 110-120K.
Today, I started it cold, it took longer than normal to crank, then it revved up to cold idle RPMs (normal), then stumbled to like 800 RPM (not normal), then back up to cold idle, and it seemed to be somewhat erratic/lopey.
I took out the MAF and sprayed it from both sides with some MAF cleaner (also did this about 3K miles ago). Put it back in. Same behavior...
When warm, the idle is barely maintained, it goes from 750RPM to 300-400 (almost stall), kinda cycles up and down like that until it drops low enough that it stalls.
If I put my foot in the gas lightly, it revs up to 1500RPM and stays there, but I can tell that it's not particularly smooth.
I can cruise the highway fine, at higher RPMs like 3K or 5K (either no load or while cruising in town), it holds them fine. Full throttle acceleration seems to be mostly there, it does not stumble on acceleration (revved it to 5.5K).
I inspected the battery contacts, cleaned the posts, voltage stays consistent at about 14.1V, so no electrical problem there. Voltage between battery positive and the ground point on the engine is about the same.
Blew into the PCV valve, it did let just a little air through instead of blocking it 100% in one of the ways, so I'll replace it just in case, but I doubt this would cause idle problems.
I think the car has original coils.
There are no check engine lights!
Could the EGR have gone bad in only 17K miles and about half a year? Seems unlikely...
I don't think it's the fuel pump, because it doesn't stumble on acceleration.
Anything else I can look at?
Should I try replacing the coils for shits and giggles? Could it be a bad MAF sensor? (But wouldn't that show up in non-idle situations as well?) Should I inspect the EGR again anyway?