Sequoia has NO power all of a sudden

Left the house this afternoon and my 2005 sequoia has no power. The car struggled to get to 70. Check engine light is on along with two different "trac" lights. Once I stopped I popped the hood and discovered the oil cap was gone. The oil pressure and level is fine.

What could gone wrong with the cap off?

 

It's probably in "limp" mode. It prevents the engine from creating anymore damage. Get another oil cap and reset the light.

 

Engine runs in vacum, so with oil cap off it can not create the vacum. If you put cap off and reset computer it should be back to normal unless you suck it so much dirt that it had damaged something.

 

Is there a way to reset the computer without a scanner?

 

You could try removing the negative side battery cable for 10/15 minutes then reconnect and see if codes are reset. If not you will need access to a obdII scanner.