GTI 16v not idling! (more to it than that though)

[AdamBeevers]

Ok, so i've searched and searched ad searched. I bought a 2.0 16v the other week and it had a few problems, plugs, leads, oil and oil filter have all been replaced.
The problem is the car wont idle, i start it up, and have to keep revving it to keep it running (sketchy to drive) and sometimes after a while it will just about idle (after the revs dipping right down then back up to about 9rpm)...

The air filter is real dirty but dont think its that, when its cutting out too the rear lights dim down loads and a battery light comes on and it cuts out all together, its not the battery as i've tried a friends and it didnt make a difference, could it be earthing or something? The car is an old rust bucket so anythings possible!

As much help as possible will be great, i'm off to euro parts now and will check my phone once i get there to see if any updates have been posted!
Thanks in advance!

[thai-wronghorse]

if it's such a rust bucket and doesnt run well then may i ask why you brought it?

[spear]

i'd change the air filter, clean the throttle body and maybe give the idle stablisation valve a clean with some carb cleaner. that might help things a bit, also change the fuel filter as that can affect the running if its not been changed for years. start here and see if it improves, there are plenty of other bits and pieces to clean/change so its going to be a process of elimination.