It's about Audi A3 from '99. The idle goes up around 3000rpm and then drop to 0 usualy when it's a little cold, but sometimes doesn't matter even when it's warm outside or the engine is warm or hot or cold doesn't matter. can anyone help me please with some ideas ??? thank you.

 

It sounds like a gasket leak somewhere, perhaps your intake manifold gasket.

 

SOunds v similar to mine - also 99 A3. Had trouble starting when warm.
Turned out to be a faulty coolant sensor, causing too much petrol to go into the mix. Replaced sensor and all fine.

 

Or another sensor - random stalls in mine were caused by a faulty engine speed (rpm) sensor.