2002 1.8 petrol starting problem

Hi, new here and have a strange one.

Been through lots of posts and spent hours reading and trying different things until this weekend when something strange happened.
Let me start by saying I am having trouble starting, on the first attempt each day seems to fire for a few seconds then dies and won't start after.
I have checked through what I can and can't seem to find a problem with anything.
However at the weekend thought I would go through a few things again and as my son was about to help thought I would start with checking for a spark. Removed number 4 plug and told him to hold it whilst I turn the engine over and look for a spark, well the car started! and he confirmed a spark at the plug. So I put the plug back in and tried again, nothing. Then removed number 2 and tried the same process, again the engine started. Obviously runs a little lumpy on three but it runs. When all four are back in it just wont start.

Any ideas? all information and help would be appreciated.

Possible coil fault? Have you checked things like the fuel pump is running? It does seem a strange fault though.

Dying battery or starter? Or bad connections between them

2002 1.8 petrol
Just ordered two coils to give that a try, fuel seems ok took off injection manifold turned key and all appear to be spraying ok