Sorry for dodgy quoting, phone sucks a bit...
"Another forum suggestion was to check that the TPS was set to 4.5V on closed loop mode"
That doesn't make sense.
"I have borrowed a set of 5 coils"
6?
"AFM has been off and it looks very clean, but I havent checked voltage through it (suggestion through skylineowners forum)"
What voltage do you expect to see and when? I don't believe a meter will tell you anything useful about your afm. Even if the afm looks "very clean" what's the harm in cleaning it to be sure?