This is a better place for this, but the answers wont change.

Changing the air filter is a good idea, and might help tho I doubt it. The issue is that THE CAR SAT.
Changing the oil is not going to clean the exhaust up, but again, as I said before, ALL FLUIDS are due to be changed anyway.

You have been given the answer by many here and on Facebook: DRIVE THE DAMN CAR, run it out of gas, fill it again and DRIVE THE DAMN CAR. I doubt there is much wrong with it.

"I can't get a tag/they only give us three days" - either stop saying that or sell the damn thing, again, I doubt there is anything really wrong with the car, other than it sat so much. Just because you don't like the answer does not mean the answer is wrong, and "answer shopping" where you keep asking until you get an answer you like, is a waste of time. Put insurance on it and DRIVE THE CAR. As I said before, you bought it in another state, every state has temp title/tags you can get for a few dollars for transport home. Those tags are honored in every state for at least 30 days - I've bought three cars out of state, different states every time, it's easy.

If it's too late for a temp tag, put the tag on from one of your other cars and dont drive stupid and get pulled over. (I've done that, too.)