Recommend cleaning the Throttle Body bore & butterfly, as this area often gets gummed with carbon & oil deposits, causing poor idle quality. That Fuel system cleaner you get & the parts store........not good, most of them actually leaves small deposits on spark plugs, seek the Fuel System cleaning of a "tune up or performance shop", average cost = 59.99, but much better than "over the counter". Also, the MIL (Malfunction Indicator Lamp) should be checked out, as it will give you a direction as to what is going on in the eyes of the PCM.