hi im new on here, just on with buying a h reg xr3i, the fella im buying it from says its got a missfire due to needing a new octane adjuster? he showed me it and said it plugs into the wiring harness and then needs to go on a computer to reset the memory of the fuel system, can anyone shed any light on this, having driven nothing but capris for years this is new to me, i went into my local ford dealer and they didnt know what i was talking about, any help much appreciated, thanks