Q: My car only starts if I cover the air intake tube where the air filter goes

This may suggest you have a vacuum leak. When plugging the air intake tube, you are choking the motor off from supplying it with air. If taking your hand off and allowing it to breathe on its own causes it to die, this means it is likely getting too much air, which is also common when there is a vacuum leak present in the system. I would suggest checking for air leaks around the intake manifold as this is often a common place for them to develop. Also check other vacuum lines to be sure they are properly connected. You may want to consider having a professional from YourMechanic come to your home to take a look at your car to properly diagnose why your engine starts and then stops.