I don't know for sure, but the EFI system on the
16V probably doesn't fire each injector seperatly,
most likely it has 2 channels, each drives 2 injectors.
That being said, it would not cause only one injector
to stick/stay open, at least get the old computer if
you have already bought a new one, other than that,
a set of wires might have been the problem, and an
Exhaust Gas Analizer could tell you if the injector is
wide open ........... Mechanics

always screwing up.