Intermittantly dies

My 1995 tdi runs great, except occasionally it just dies for no obvious reason (only at low revs so far).
No problems at full revs (so far) but I am worried it will die one day at a very inopportune time. It can be fine for say 6 months, then one day it just dies with no warning. Lately it has been doing it more often, maybe every 2nd month? No misfire, no smoke, no warning.
I then spend about 10 or more minutes trying to start it again. During the attempts to start, I move the auto gear stick back and forth, let it roll a bit try long engine turnovers, and short, throttle hard or none. Nothing seems to make a difference, then suddenly if I wait long enough it fires up and I'm ok for weeks or months. It does it when the weather is hot, cool, wet,etc. Nothing consistent about it.

I wonder if its fuel or electrics. Maybe a loose wire on the security module killing the engine or on the automatic gear selector? Fuel seems clean.

There will a electrically operated fuel cut off valve somewhere on your engine, your problem could be a loose connection to it as it needs a constant 12v to keep the engine going, on my 96 300tdi without EDC or EGR its on the rear of the injection pump and has a single black wire to it, that fits onto a male spade terminal.

The valve is needed to provide a way of stopping the engine, it will also be part of the immobiliser circuit.

Other possibilities are faults in your fuel supply eg filters/pump/pipe leaks etc

Check where the cables come thought the bulkhead more than likely the grommet has slipped and the insulation on the wires has failed. I had this on a prev disco.

If its not electrical which it might be.Have a look at the bends on top of the fuel sender the ones coming out of the top of the fuel tank.A friend of mine had a nightmare of a time with his disco cutting out.Turned out to be hairline crack in one of those bends. Found it by accident when he was changing his sender unit.

Hmmm. I'd be thinking fuel issues too

Thanks Guys. I'll have a look.

As said above sounds like a problem with the stop solenoid on your fuel pump. Hopefully just a bad connection.

I found the problem. Its in the ignition switch somewhere. I just have to wobble it a lot when trying to restart.