The problem started a few days ago around town (max speed 50k) - the car started ok, but with no warning, it just slowed to a halt. Wouldn't restart. I was nearly home, so I walked home and went back later and it started fine. The next day, all good for the first 10 minutes, and then the same thing happened at 2 roundabouts and then at a stop sign. 3 stops before it refused to start. Went back later - all good.
Today I took it on a longer run (max speed 110k), and it was surging intermittently, the revs were fluctuating between 0 and 4500. If I put my foot down, it revved up, but took a moment until it actually kicked in.
I have had the car about 9 months, and during that time, most of the wiring has been replaced, as has the fuel pump relay and IAC. Fuel pump relay and IAC just about a month ago.
I apologise for my lack of techinical detail, please ask if for more if you think you can help.

 

I've had a hall effect sensor go bad intermittently before it completely died. But you also say that you had the wiring replaced. Check the grounds, especially the ones that ground to the intake manifold. Make sure that they are making good contact. Good Luck.

 

Thanks TJ!
Turns out it was the ignition module. It kept cutting out intermittently until it stopped altogether, making it easier to find the source of the problem.