P0605 Internal Control Module ROM Error
The P0605 will show if there has been a progrmmer or chip installed on the
PCM. If there is not one of these installed then you need to trace this code further. If there is a chip or programmer then disregard this code.
This is some of what I found while snooping around -- seems it could be lots of things.. do some searching for that code on some
PSD sites and you'll find all sorts of stuff to check. Another thing was the
ICP sensor plug may be dirty since you changed o-rings and might need to be cleaned...