89-91 maximas came with the vg30e and the 92-94's came with the dual cam. 95+ is a VQ. Those harnesses are known to rot and ground out around the fire wall and other tight areas. the coil packs (as tampamax said) are also known to go out. common problems...i'll check TSB's on that if you want me to tomorrow.
Is there reference voltage at the injector plug?