Take a look at these 2 diagrams and pull the EGR (Exhaust Gas Recirculation) valve to clean its pintle and passages. At the same time pull the EVAP solenoid which is stuck into the "driver's side" of the throttlebody casting. That valve and its associated vacuum lines can be a source of a nagging miss.
After that, get a 20 oz jug of Chevron TECHRON gas additive, dump it in and fill with 93 octane Chevron, Texaco, or Shell. (Google "top tier gasoline" for info). Go for a long drive and do a couple of WOT runs.
Here's my carbon-cleaner procedure: On a long, straight stretch of quiet road, from a slow rolling start, put the stick in 2. (From here on the transmission and engine WILL NOT let you break anything.) Turn off Traction Control if possible. All clear ?? Punch it ! Stick your foot through the firewall. The 1-2 upshift will come at about 6,300 rpm - redline - and you'll continue up to close to redline again, about 75+ mph. Flip your foot off the gas and let the engine pull the car back down to 20 mph, no brakes. (If you miss the foot-off-the-gas at 2nd redline, don't worry: the transmission will upshift to 3 and continue happily on up. Back off anyway. The transmission WILL NOT downshift until vehicle speed is safe for engine speed to increase in the downshifts.) Lots of black crap out the tailpipe ?? Calm down and do it again..............Why ?? This procedure heavily loads the pistons and rings, breaking down carbon deposits. On engine pulldown, the cylinders unload and go to high vacuum, allowing the piston rings to rotate in their grooves and shed carbon deposits. Couple of times a month. If you're uncomfortable doing the Full Monty the first time, ease into it with maybe a high rpm first gear run to get the feel of your car.