yeh it's got to be AFM related.
if not the AFM, then the plug, if not the plug, then the loom it's connected it.
the engine bay gets pretty hot on a daily basis.
heating, cooling over and over for 15 odd years.
plastics and so on are going to get frail.
make a small change like removing the air box to fit a pod and you have to disconnect the afm, the plug, bend stuff around to remove things...
things can break/split.