Why does my Ford S-Max lose power while driving on highways?

My Ford S-Max seems to run perfectly fine in city driving, but when I'm on the highway it starts to lose power and feels sluggish. I've changed the air filter, fuel filter, and spark plugs, but nothing seems to be helping. What could be causing this issue and how can I fix it?

This could be a sign of a clogged fuel injector. I suggest getting it checked and possibly cleaned or replaced. Also, have you checked your exhaust system for any blockages? That could also cause a decrease in power. If all else fails, take it to a certified mechanic for a diagnostic test.

I had a similar issue with my Ford S-Max and it turned out to be a faulty oxygen sensor. Make sure to get that checked and replaced if necessary. It's also a good idea to regularly clean or replace your air filters to ensure proper air flow.