[spud31]

Has it had a clutch recently ?
Try replacing the main earth lead to gearbox with a descent jump lead as the earth lead is easily damaged an goes v high resistance giving symptoms uve got.
If also sure these have a starter relay worth checking that.
If uve vagcom check the measuring blocks for the MAF as these dying and giving low readings give a poor starting condition.

done some digging engine needs to be spun at 240rpm+ for fuel system to start injecting fuel, both this an Injector pump timing can be checked in vag.com