Originally Posted by andyr

Common issues causing warm start problems are the 3 following sensors :
Coolant temperature
Crank position
cam position
I had this issue, swapped the sensors in the above order, was only when I installed a new cam position sensor was the problem resolved and it then started fine every single time from then on.
That sensor was thought, I beleive, NOT to be used during the start-up process but it was certainly the one that did it for me.
Coolant temp sensor was the worst to replace (at the rear to the left of the engine block) so I'd maybe start with the cam or crank position sensors and see if they resolve your issue.
Not mega bucks brand new (£30 - £40-ish) but you might try to source a s/h one if you want.
If I recall, when the problem happened for me, if I unclipped then put the sensor back on it would often clear the problem.
Crank sensor is at the front of the engine, cam sensor to the right hand side.

Have you run through the CEL procedure - I recall the CEL lights gave me some slightly unreliable results.