The 2.4 ECU isn't compatable with the 3 Ltr & the manual also. I've just had my Surf off the road for 5 whole months with an ECU problem as no garage could identify the exact fault! I'm suspecting that you have the KZN130 model? If you have an ECU problem, you'll be searching for donkeys, probably to no avail. Toyota Japan have even stopped making them (were around the £600 mark anyway!).
This guy in Plymouth is fantastic, he fixed mine for £160 ish & it sorted out a few other niggly problems, like Overdrive not working etc.
Hope this helps