A couple of possibilities, i have experienced
Take off the cam belt cover, turn over the motor and watch the three cams to make sure they are moving properly. I had a cam bearing/woodruffe key fail which meant the cam wasnt completely turning or lifting anything. Engine just would not go.
Failed/failing ECU/VFI...engine wouldnt fire/tick over but occasionally would run at high revs/throttle. Auto electrician found that the ECU was firing injectors 4 times at start /low rpm but once at higher throttle. Effectively flooding motor.
Hopefully havent added to the confusion
