Is the maf the sensor with the 5 pin plug going to the filter box?
On a 1.8 it should be half way along the intake pipe near the right hand end of the engine cover. If it goes to the filter box, you've got a V6 box!
If someone has been playing with the throttle, it may need resetting ... there is a simple way involving the ignition switch and a more complex way that needs AlfaDiag or FiatEcuScan.
The easy way is:
1) turn on the ignition but don't start the engine and don't touch the throttle and leave it on for 90 secs
2) turn of the ignition and leave for 90 secs
3) start the engine WITHOUT touching the throttle and leave it to idle for a couple of mins (hard I know with the price of fuel!). It should settle down. If it doesn't go back to step 1
4) turn off the ignition, restart and go for a drive
If this doesn't work, then the idle actuator may need to be reset and for that you need a diagnostic system.
Or you have another problem and that could be a lambda sensor .. they usually cause the revs to fluctuate as they can affect the fuel mix ...