'scuse my ignorance, but where exactly is the MAF sensor?

'scuse my ignorance, but where exactly is the MAF sensor?

After the airbox, connected to it by 2 screws

however another maf which is believed to be good has been tried and made no difference

Believed to be good, therefore could be bad. If disconnecting it made it better I would imagine you have found the problem. Try a new one or one that is known to be good

It also doesnt hurt to change the air filter as well, they are around £10