300tdi fuel cut-off and spiders?

Ok, a bit of background, over the last 6 months or so sometimes I am driving along and the engine cuts out, turn the key of and on again and the engine runs again. I would like to sort this out, so far it has not happened at a critical time.
So I was thinking that maybe the fuel solenoid has an issue or poor connection perhaps? unless it is something to do with this spider I keep hearing of, but know nothing about?..anyway that was until the other days events and now I am really confused.

The night before last someone tried to steal the landy, they smashed the steering lock and then must have found there was no power due to the isolator switch I have in the battery box. They opened the battery box and presumably couldn't work out a way to get the isolator on. A very lucky escape for me that they didn't have the tuppence ha'penny plastic key for the switch....More security required!

So here's the thing. I switched on the isolator and turned what was left of the ignition switch with a screwdriver and hey presto it fired into life. When I tried to turn it off the engine just kept running so I was looking for a way to stop it. In hindsight I could have tried to stall it but I didn't. I opened the bonnet and pulled open the 3 wire connector on the fuel pump...and it still kept running! I thought this was the crux of the engine immobiliser and was probably where my original cutting out problem came from and was certain the engine would not run like this? any ideas?

Which plug on the pump was it as the cut off is at the back down quit low

3 wire on the top is the EGR control,
the one on the back is either a single black wire, on a spade, or the antitamper type which AFAIK is fixed/sealed wiring.
needless to say unplugging the EGR will do not alot.