Engine detonations - poor or rich fuel mixture??

What causes detonations in inlet collectors?
Poor or rich mixture....or both can do it.I'm still have some bang-bang when start cold engine, and i'm concerned about.
Here you can hear sound of my engine, started cold in the morning, and no touch of the throttle.
http://hitspaces.net/engine.wma
To explain what do you hear - when engine is on, revs are 600 - 800 and it seems like it will die instantly - this continues 10 - 20 sec.(you may hear first bang on 22 sec of this record) and then it's OK - 1100 - 1200 rpm, and working perfectly.
More - when i start cold engine and shut it down immediately after starting, and repeat this 2-3 times, on the 4 starting it's OK....no detonations. My fuel tank cap is not original, and there is no pressure in the tank at all, and i know that there must be some. Can this be a problem?
I changed 8 new Denso iridiums.New Bosch MAF and lambda!!!! No change.......
Thanks.

i also get this with my car and would liek to know the solution?

TRy to measure fuel presure when engine's cold......

I think you may find this is your pre-cat sensors if your car has the twin cans at the manifold outlet, your lamdas there are faulty.