Loss of power

Turned car on and attempted to drive it. Check engine light and another light that looks like check engine, but with a down arrow over it appear. I floor the accelerator and can go less than 5mph. If I touch brake or turn corner, car silently dies. Restarts and off we go @ 5mph. If I can keep going, it will eventually gain a little momentum. Turned car off and let it set. Tightened gas cap and it the check engine with the arrow light went off, car drove like normal. Later, freaks out and we're back to 5mph. On a super tight student budget until hubby graduates and just trying to figure how major it's going to be.