If it just now started after buying gas, I'd lean toward bad gas. Running the tank down and filling at a trusted station would clear that up easily.
Aside from that, I'll part with DJ's advice on the RCM (always a good idea to have him refurbish the RCM, don't get me wrong) and suggest that, if the engine runs fine at higher throttle but is rough at idle, I'd suspect a vacuum leak or fouled up MAF.

One way to determine if you have a bad vacuum leak:
Start engine.
Drive it and warm it to operating temperature.
Stop, put in Park/Neutral.
Pop hood.
Now, yank the oil filler cap off.

If the engine does not change how it idles, you have a bad vacuum leak.
If the engine surges and shakes and struggles to keep a stable idle speed (at least in the first 15 seconds), then you have no vacuum leak.
You see, yanking the oil cap off creates a HUGE vacuum leak - if the engine does not notice THAT, you already have a vacuum leak.

The RCM is always suspect, personally, I lean towards bad gas, a filthy MAF or a vacuum leak.