AT 56k miles now...

Car has developed a distinctly rougher idle than normal, not misfiring. But it used to be (20 or 30k ago) you couldn't even hear or feel the engine idling at all. Now it vibrates noticeably and you can definitely tell the engine is idling kinda rough. Also, sometimes this week, when starting the car, the engine has taken 5-6 extra seconds to start (it usually turns over 2 or 3 times max (about 1-2 sec.) and fires right away.) Seems to happen mostly when the temp goes from cold to warm (like the other day it went from 30 at night when i parked to 60 when i next started the car.) It idles at a fairly steady 625-650RPM when warmed up but the tach needle has been bouncing a bit between 500-700.

Related work done already...

New MAF @ 35K (as part of hesitation TSB)
Crank/cam sensors replaced per recall
Fuel injection pressure flush using BG44k @ 53k miles
Throttle body cleaned at 53k using Gumout TB cleaner
2 new rear 02 sensors + ecu flash (O2 sensor TSB)
2 evap leaks fixed in vacuum hoses.

No codes stored in the ECU...

Suggestions? It's on the OEM spark plugs...go there next and replace?