my 78 280z recently started to lag when starting, it would take 2-3 turns of key to start. But know it just dosent start. If I use starting fluid it starts right up. Once the car starts it dosent turn off, but the car feels a little shakey in first unless I really push on it. A friend told me it could be a bad injector if so how can I check witch one. has anyone had a similar problem.

check the fuel pressure, that is you're first step.