What year is your gf's car?

You can run it with the 1.8 ecu, but at the top end you might not get as much power as running with a 2.0 ecu, as i said, people have run tehir 2.0's on the 1.6 ecu for a trial period. If its a 130ps ecu your current 1.8 one then it will be fine, if its a 115 then you will be down on power.

The ecu will connect directly to the loom, but you will have to find out if your car has edis thing internal or external. I think in most cases you will be aloright using the 2.0 ecu from a mondeo, but it needs to be either dewy, desk or deep. Basicly find out if your edis is different from the mk3.5 zetec fiestas, if it isnt, then the above ecu's are the ones you need to look for and they will conect directly up.

You will most likely have to use the 1.8 flywheel (definetly if the escorts didnt come with a 2.0 engine) but the crank sensor will only need changing if the engine came from a automatic car. When i did my engine conversion i didnt touch this.