help

Hi folks, Has anyone had this problem and if so did you have to go to stealer to get it fixed.

05 octavia elegance not put a foot wrong since I got it. But recently the engine light came on so took it to local garage who said it was the heat sensor but they changed it and light still on so they think its an underlying issue. as of late the car now runs at high revs especially when cold but does happen when the car has been running for a while. if anyone remembers automatic chokes its similar to running a car with the auto choke on.

Just wondering if anyone has any ideas before I go and get screwed over by stealer...