Power loss and engine cut out

[Gem]

This morning as I was driving along and I suddenly felt the car lose all power, there was nothing there at all when touchign the throttle, and it was just running on momentum.  I pulled into the side of the road and whacked the hazards on and that was when I noticed the engine cut out.  I couldn't say if it cut out at that point, or had cut out earlier as the radio was on so I couldn't really hear.  I *think* it cut out at that point as I noticed the red battery light come on and realised I'd lost the engine.  I turned the radio off and tried to start the car again, it started up fine and as there was a break in the traffic and I seemed to have throttle response again, I pulled back out.  Car ran fine after that.

Any ideas what could have caused this, it was really odd.  It literally just lost power quickly and suddenly, no coughing or spluttering like it would with a fuel issue.  I did wonder if it might be alternator but it wouldn't have started up again if that were the case. 

Some electrial fault maybe?  Battery terminal not tightened up enough perhaps?  I had just put the battery back on it this morning after a nights charge.

Cheers guys and gals

[steviem]

In my experience with other cars, never happened in the 4 whole days that i have owned a GTI, a loose connection on a battery terminal can cause all weird stuff to happen, so make sure the connections are all nice and tight and you shouldnt have those probs, as you only put it back in this morning thats the most likely cause, i think.

[Gem]

I did wonder if it might be that, but the radio didn't cut off which made me think maybe it wasn't battery connections after all.  Is it possible for there to be a slight break and the connection goes enough to cut the engine but not everything else? 

[Organisys]

Check all your earth straps, including the one on the gearbox?
 

Edit: I can't type it's a monday ! 

[Mk2Kezza]

Am i right in thinking that if the battery terminal came off then the engine would still run fine as the battery only helps to start the car?
You would have had a problem starting the engine back up though, so maybe not that?
As Organisys has said 'th eon eon' or even the one on the gearbox!!

[rubjonny]

Could be the Hall sender beggining to go, or possibly the coil.  First port of call is to give it a full service, dizzy cap, rotor arm, sparkies, filters etc