Punto does not start or leave during the ride

Moinsen love community I have a Punto Bj. 01 and this is the phenomenon that he (so I can see it) when it is cold, does not start at all or (and that is always sporadically) after approx. 100-200m simply runs out. I have already made the fuses and relays, everything out and sprayed with contact spray all plug connections. Even our Fiat dealer is questioned (bin with the per-du ^.^). Now I hope that one of you can help me here…. De nn I must already be able to rely on my car (professionally). My brother has already the neck that I always take his car 😉 Thanks already in advance mfg Rene