Usually the MAF code comes from an air leak into the system somewhere rather than a failure of the MAF. EU does have different engines and engine management systems we aren't so familiar with , though. The wrong MAF can definitely screw up your gas mileage Can I link this post to the " help,a n...

It could be the wrong MAF was not recognized by the ECU and it just rAn from the lookup table. I ran 200 miles like this once and got the same gas mileage as with the MAF hooked up

If the MAF is unplugged, does the idle still surge? If so, odds are it isn't the MAF causing that particular issue.