Had a go at blanking the metering head oil return hole and it hasn't made any difference.

I've noticed that the car does start from cold although it is mis-firing (it's got new plugs and leads). After a few seconds it then stalls and won't start again.

Checked and double checked that I've put everything back together properly and everything seems fine. The only thing I'm thinking could need looking at is the mixture. Is this something I could adjust to get the car running again and then get it looked at by a pro?

Also, any other pointers as to what I should be checking given the symptoms described previously?