If you don't have a job and only have $50, I suggest you hang on to that until you have steady employment.

Which wouldn't be hard to acquire today. You should be able to be working tomorrow by 10am. Go get a job somewhere. Anywhere.

When you get a steady income, change the stuff mentioned above. Could your driving habits stand a change?

After changing the plugs, fluids, filters, etc., along with habits, you still don't see an improvement, take it to a mechanic who've you researched to death.

Get him to tune it up.