Auto

drain the fuel and use fresh gas.

(new plugs if they are easy)

from there, be careful and see what happens.

Fuel draining is oftentimes real bitch I would simply:

- add a batch of fuel injector cleaner
- add a batch of water absorbing additives containing isomeric propyl and butyl alcohols
- fill the tank up fully with new fuel
- make sure the battery is in good condition and fully charged
- give the vehicle a good overall inspection in particular the engine bay for unwanted creatures and lose fittings etc
- check air filter
- check all fluid levels

Try and start it!