What are the common engine problems in a Ford Focus?

I recently bought a used Ford Focus and I've been experiencing some engine issues. What are the common problems I can expect with this car model and how can I prevent them?

One common engine problem in a Ford Focus is the ignition coil failure. This can be prevented by regularly changing the spark plugs every 30,000 miles.

Another issue is the failure of the electronic throttle body, which can cause loss of power and engine stalling. It's important to regularly clean the throttle body to prevent this problem.