I read this tread for 5 times and I guess you bought a new MAF from eBay and not a Bosh so in fact a generic thing which won't work. You want to use either a 68mm MAF + Throttle = stock from Bosh or do the 74mm mod = MAF housing + Throttle body from Bosh.

Moreover I read that your original MAF isn't working properly so
1 you need a new MAF with Sensor from Bosh
2 don't buy generic MAF/Sensor
3 keep it 68mm stock or do the 74mm throttle + MAF mod from BOSH only ( used works too )
4 onve you installed the new MAF either 68 or 74 do a throttle reset, it didn't work for me so I just unplugged the negative batterie for a hour and then it worked.
5 any questions ?