I'm trying my best to sort out my daughter's 16v MK2 GTi and seem to be going backwards. There's so much good stuff in this forum elsewhere, but the stuff that's happening seems to be designed to stop me getting the car stable enough to apply most of it! I suspect that I've just missed something obvious

, but could really do with some advice if that's possible.......
The car started to run rougher and rougher over a couple of months (I know, I should have stepped in earlier, but I was hoping her boyfriend would help out this time

). I did insist on changing the timing belt, as it was over 5000 miles late (and maybe an entire change out, but we won't mention that here

). This made no difference to the running, and over the next 3000 miles it slowly got harder to start but seemed to run OK when it was warm.
In the end I decided to try to set up the timing, but couldn't get a timing gun to even light up. I tried 2 guns and both work fine on my Rover so I'm thinking that there's a spark problem. The problem was on more than 1 plug, so I tried swapping the coil. this made no difference (I then swapped the coil back) and changed all of the leads, plugs, distributor cap and rotor arm.
At the time, the engine was starting but after a few seconds the revs were dying, or if I pushed the accelerator, the rev's dipped down, and if I timed it right came back up, otherwise just died. I just went back out to try again (a week later), and now I can't even get it to start. There's a smell of petrol and when I get someone else to turn the engine over, I still get no flash out of the timing gun. In fact I was getting a dull background glow in the timing gun before, but am getting nothing now.
So, can anyone shed any light on this for me (excuse the pun!)
thanks