Hello and welcome
Its probably FUEL FILTER, outside the engine,
Try spraying carb cleaner into ur air thingey with the plastic removed, if ur engine runs it means is fuel delivery.
Theres also a filter inside the FUEL tank, i dont know bout paseo but tercel one is right under seat. That can get clogged with large debrees.
air intake might be clogged with crap if ur plastic was damaged.
Also my other car "KIA" had a transmission problem, it might be that if ur transmission is automatic.
Injectors can be tested with a regular volt meter set to resistance, mine read around 14 OHMS whatever the hell that means. The repair manual says that that means they work well. If urs doesnt work well, u can get them cleaned by a mechanic, where they run cleaner through em, or u can get a new one, Im not sure bout paseo but the tercel ones i saw on rockauto.com for like 30$ which isnt bad considering ebay was like 90$ for ONE injector..,
If u got a carburator, u might have a problem with ur needle it imght need adjustment im not sure how that works. if its injected u can also adjust the opening of the thingey with a screw driver, and also adjust the IDLE CONTROL sensor,
Thats all i can think off LOL! i suggest get a repair manual and check out the symptoms, i got mines from ebay for like 15$ and another for 5$
Goodluck