does stilos after 2002 still have computer problems? like airbag and ecu? im looking in getting a new car and im a bit worried about what iv read so far.
anyone can give me some advice?

Most problems are caused by poor connections, clamps and dirty contacts. Make sure a good quality battery of the correct size fitted.

The 1600 model I believe had issues with engine ecu due to its location.

The airbag can give faults if the passenger seat sensor gives trouble.
This can be cured by fitting OCS Passenger Seat Occupation simulator
Guide here
https://www.fiatforum.com/stilo-guides/423782-ocs-passenger-seat-occupation-simulator.html

As said above, many phantom electrical issues on the Stilo are due to a poor/failing battery. If you're thinking of buying a Stilo, you may find this of interest:

https://www.fiatforum.com/stilo/273562-buyers-guide-fiat-stilo.html