vw golf 1.8 gl 1995- Wont start!

Changed the leads, plugs, rotory and cap. Starts most of the time but in the real cold or dampness it wont start. A mechanic changed the cold start valve but he said it may of 'shorted out' on fitting as he forgot to turn ignition off prior to fitting! I;m going to change the cold start valve agian but can anybody think of something i may have overlooked or something i should try? Please help 

You want to try to narrow down why it doesn't start.  A car needs 4 things to run:  1- Compression  2- Air  3- Spark  4- Fuel.

If the car runs good when its warm, compression is not a problem.

If the car has a problem with airflow, it would start hard in all temperatures.

It CAN be a spark problem, but the chances of it are next none.  The easiest way to check spark is to remove one of the spark plug wires, stick a screwdriver into the wire, lay it across a chassis ground point, and turn the key.  Have someone watch for spark.

Fuel could also be a problem.  It takes more gas to start a car when its cold or damp out, so it could point to a weak fuel pump, or the cold start valve.

Thats about all I can tell you right now, I'll see if I can think of anything else.

I hopes that helps a little.

-Jason