Just picked up a new car and I need some help diagnosing a rough idle.
Here are the symptoms: cold start is smooth, but as soon as it comes off high idle, it starts to run rough. Anything off idle is smooth, drives fine otherwise.
What I've checked so far: cleaned PCV valve, checked for vacuum leaks on the intake manifold, cleaned throttle body and IAC.
No codes. Unsure of when the car's last tune up was.
I was going to pull the plugs and check them next. Any other things I should be checking?

Car has 174K miles with a newer engine with approximately 50K on it.

Thanks.

-Dave