Engine not running right
 

Hi i have a 2005 with 24000 KM (15000miles) with engine running a bit "off" lately. ive had regular maintenance done to it and it only has a aftermarket air filter done to it. ive never flooded it and i always drive it hard.

so this is the story. its a week now that the engine is ruff to start, it hesitates almost chokes and then starts. the engine still runs but feels weaker more like 80% capacity. gas milage is bad, and sound of engine isnt smooth, sounds a bit grindy instead of the clear whining sound when i push it hard.

I took it in today to get checked, the stealership said my plugs were dirty and were misfiring. those pricks changed them and then said everything was perfect, but the car is exactly the same as before i took it in. i searched a lot on the forum and im still not sure whats next that could be the problem... coils, bad cat? anyone have any ideas? im going to bring the car in again on monday since nothing got resolved, just emptyed my wallet for nothing and pissed me off. anyways let me know your ideas. thanks

good spark? (plugs, wires, coil)
good compression?
good cat? (not clogged)
getting fuel?

If your car is carbureted, I would try pumping the gas pedal a once or twice before you start it the first time. This will both reset the choke if it failed to do it on its own, and add a little extra gas to the cylinders to aid the cold start