The fuel injectors in your Fiat are susceptible to clogging, particularly if you use low octane gas. This can cause your engine to misfire. It's in your best interest to clean your fuel injectors periodically. You can save yourself the trouble of having a service technician clean the injectors by doing the job yourself in your garage, which shouldn't take you more than 10 or 15 minutes. Ideally, you should clean the injectors at least once a year.
Park your Fiat, turn off the engine and chock the wheels. Walk around to the front of the car and prop open the bonnet. Release pressure in the car's fuel system by screwing off the fuel cap, then screwing it back on.
Locate the fuel rail which, as the name suggests, resembles a rail or pipe, and is lined with the vehicle's fuel injectors. Hook (or in some cases, screw) the cleaning solvent tool (which should come with the cleaning kit) to the fuel port, according to the instructions that come with the kit. Disable the fuel pump by going into the fuse box and taking out, or disconnecting, the fuel pump relay.
Hook the air supply up to the tool holding the solvent. The air will power the tool. Start the engine to cycle the solvent through the fuel injectors for about five minutes.
Turn off the engine, and detach the air supply from the cleaning solvent tool, which you will then disconnect from the fuel rail. Finally, replace the fuel pump relay.