Right I have a Nissan sr20det I have replaced the air flow meter, idle control valve done a compression test and new plugs all fine. But am still struggling to starty car. If I want to start it I have to open and close the throttle as am turning it over then it splutters into life.

I fitted a fuel pressure gauge and am getting 3bar of fuel pressure but when it primes I can hear what sounds like air rushing through the fuel system. Once the car finally starts it runs fine and drives spot on.

Any other ideas 5p what mabie stopping it from starting up.

I dont know about that engine, but its quite common that an engine temperature sender can cause similar problems. (ie ecu thinks its warm, but it is cold and needs 'choke' / 'fuel enrichment'

crank sensor?
Have you tried one of the plug in code readers to see if anything comes up?