Thought it was about time I squirted my MAF so unplugged the "plug" and loosened the irreplacable screw fixings, withdrew the MAF and gave it a copious amount of carb cleaner, as I was about to replace it, I remembered the Bosch air filter I had bought some while since, loosened the filter lid and set about changing the 2014 filter [stamped on side] then noticed the filter housing was loose, front and bottom bolts/grommets OK rear "Peg" grommet was missing, this is where an irregular rattle metalic/clunk had been driving me crazy for months, bought one from Toyota Northallerton £4.20. fitted sorted! [Remembered to refit MAF]