Welcome! You've come to the right place for your S30.
Without knowing any history of your car, hint hint, I'm assuming it has sat for long long time before you got it. If that is true, the first thing to do is change all your fluids, including any old fuel in the tank. With the EFI I would go ahead and replace every vacuum hose. They will probably be cracked or rotten. Those are pretty easy. Do a complete tune up, cap, rotor, plugs and fuel filter. Get all the basic stuff done so you can zero in on whatever ailment is happening.
Also, download the FSM for your 76 here http://www.classiczcars.com/files/ and get the EFI Bible also. Very valuable tools that will help you understand the Z. The great folks here that are going to help you are going to refer to these often and I suggest you at least be familiar. The more accurate your description of the problem, The more accurate the replies will be.
Good Luck!