How do I troubleshoot a rough engine on my Ford Galaxy?

My Ford Galaxy's engine has been running rough and I'm not sure what the cause could be. I've noticed a decrease in power and an increase in fuel consumption. What could be causing this issue and what steps should I take to fix it?

The first thing you should do is check your spark plugs and ignition coils. They could be worn out and causing misfires which would lead to rough engine performance.

Another possibility is a clogged fuel injector. You can try using a fuel injector cleaner to see if it helps improve your engine's performance.

I had a similar issue with my Ford Galaxy and it turned out to be a faulty oxygen sensor. It's definitely worth checking out if none of the other solutions work.