Hi Kezza,
Seems that you and CPD are experiencing similar problems, just different signs. My guess is that both computers in each case are dying or are close to it.
Check with some wreckers for a HICAS unit (SSS /Just Jap/ ebay perhaps)
Simple plug and play computer located in the boot on the upper inside of the boot line near the battery.
Try that guys see how you go.
Better yet, get a mate's car and play swapsies and see what happens.....
Cheers
Loz