Ok - here's the latest.
I disconnected the MAF sensor. The engine ran for a few seconds, surging and then died. Didn't get a chance to take the vacuum line off the fuel pressure regulator to check for suction because the engine won't start again.
I was checking over all the vacuum lines and noticed what you can see in the attached picture. It looks like there should be something attached here but I can't see anything that looks like it fell off.