Yesterday when I drove my car, for the first time 2 days, the engine was sputtering on idle. Then I topped up the coolant and it stopped sputtering on idle, now it sputters everytime it goes over 2000RPM. The acceleration is choppy and is sputtering in my best description.

When I checked the fuel economy it went all the way to 18L/100km. On average I get about 12L/100km in the city. It’s staying at this insanely high number. Not sure what the issue is, previously I was driving in fall weather but now it’s around 5 degrees or lower normal.

This is a ford fusion 2006 with around 300000kms.

Any idea what the issue or issues could be?