mk3 gti 8v engine cut out help

[stainesy]

ok i have a 1998 mk3 golf gti 8v
car has never let me down.
untill today.
lastnight i was driving home i pulled out of a junction and it felt like the engine died but then it was fine. i thought it must have just been me putting it in 4th by accident or something.

well today i was sitting in traffic at a set of traffic light. engine was idling as it was red light and suddenly engine just died.
then car just refued to start. i tried and tried but nothing.
so i got out car opened bonnet and had a look around, couldnt find anything rong.
i then got back in car tried it again and it was fine. and has been fine ever since.

any ideas what could this be.

i will explain abit about my car as it may help.
my car is very winey even on tickover it wines slitely. it has always been like that since i bought it a year ago. not sure if that is a reason for anything but best to be thourough
also on tickover my car has a very very slitely lumpy twich and always has like its smooth but every few seconds theres a little shudder that is very small does not show up on rev counter.
also if i rev the engine very slitely i get i small pop from exhaust just after rev.

any ideas why my car has started to cut out then be fine?
just changed ht leads not that i think its that but as a pracotion.

any help welcome

[Sii]

This gets covered loads: I know because it happened to my car.

If it cuts out in a very dramatic way like the power has suddenly been cut then most likely it will be the crank position sensor located under the engine mount near the oil filtre. The wires break down over time.

If it dies in a lumpy, gradual way then it's likely to need the throttle body cleaning out which is very easy to do yourself.

Have a search on 'cutting out' as there's pages and pages of it! 

[stainesy]

Yep it cuts out as if power has just bin switched off. One mine fine then DEAD.

[rubjonny]

do oil and battery lights come on when it cuts out?

[stainesy]

I can't realy remember mate. I didn't think to look. I think I remember seeing them on after it cut out a moment ago. Engine was running and I was under bonnet having a look. Then it died and when I went to start again I think they were on why? 

How easy is it to change that sonsor myself? Can't find it in haynes manual.
Also are they expemsive?

[rubjonny]

if the lights come on you know its not an ignition switch fault
does sound crank sensory to me my abf did the same thing. gsf sell em cheap and its not too hard to do once you take front engine mount off

[stainesy]

any chance somebody can give me a step by step giude how to change it?
i just cant seem to find it in my haynes manual.

[stainesy]

aha think iv found it. would the crank position sensor be called the engine speen sensor in the haynes manual?

[rubjonny]

sounds like the one aye, its down the bottom of the engien next to the gearbox, just under the front mount/oil filter housing

[stainesy]

Nice one cheers mate.
Haynes manual don't say anything bout removing engine mount.
When you say cheap what we talking £20ish?