long running saga will try to edit as much as poss.car failed mot on many things some months ago.owner repaired some of the failures himself over a period of a couple of months then re-presented it for some more repairs then retest.engine was misfiring and brought fault code up for coil cct a.changed plugs and leads and coil (non-ford) but misfire remained along with fault code.ecu sent for repait to act.- returned replaced coil on their instructions and tried starting .coil went up in smoke after 30 secs .ecu sent back for re-repair.returned and restarted with another coil.bingo no misfire at all but after going through its checking sequence 2 fault codes are thrown up for coil cct a and coil cct b with mil illuminated.if the codes are cleared with engine running the codes do not reappear till next start up.two ecu repair companies are happy the ecu is ok but i still suspect it.i would like to use a secondhand one using an exact match of the numbers but am getting reports i need to change a number of other items inc instrument cluster to overcome the immobiliser.can anyone explain what and how i have to do to fit a used unit to eliminate it from the diagnostics .ids is available but have nit used it for matters like this and lack some confidence to try incase i totally screw it up .thanks in advance paul