Hi, it may be worth checking the two purple relays located in the rectangular black box that sits on top of the ABS unit. They are identical, one is the fuel pump relay and the other nearest the front of the car is the engine management control relay, which controls the injectors. Ensure the ignition is switched off to ensure no EML light appears, take them out one at a time and clean the terminals with some emery paper then lightly smear some vaseline on the terminals and replace them.
If either of the relays look brown or are bulging then best to replace it.
The GM part # for both relays is: 90494959