is the ecu in my corsa the fault?

i have a 97 corsa sport that needed a new engine, thought it was the best option as (a) i had 1 and (b) the head went in the original, after replacing the engine with the new 1 that was running fine when taken out, the car runs on 2 cyclinders, the injection system seems at fault as it running no.1&2 poorly, no.3 constantly and starving no.4, have changed the injectors, rail, coilpack,crank sensors and cam sensor to find no differance in the running, spak is found on all four cyclinders, is there a way to reset the ecu on these cars ?