Car cuts out when i take my foot off gas pedal?

I have a 03 ford fiesta 1.3 petrol. My car keeps cutting out any time I take my foot of the gas pedal. Sometimes it won't even start if I don't give it some gas. At first this happened once in a while now it's happening the whole time. What can it be? Also will it be expensive to get fixed?

Might be an issue with fuel pump or clogged fuel line - get to a mechanic

Ford Siesta

Watch the video Ron sent.

Check also for vacuum leaks and hoses that are disconnected.

If it runs good when under power but won't idle then maybe the IACV (Idle Air Control Valve) is malfunctioning. It could be stuck or maybe the plug came loose.

If not that then maybe a TPS (Throttle Position Sensor). If not that then may be a vacuum leak, a fairly significant leak if it won't idle. There's also a chance your MAS (Mass Airflow Sensor) is dirty. When was the last time you changed the air filter? There's no such thing as a maintenance free car. You must keep them up or they will let you down.

Dirty MAF sensor… Clogged IAC valve… Not very expensive to clean these items.
PVC valve… Only a mechanic can tell which…

Have a mechanic check the fuel pressure, IACV, TPS and MAF sensors. Suspect a weak fuel pump or bad fuel pressure regulator.