Engine light on-multiple dtc's..please help!

[ginapic21]

I have a 2002 protege and have 4 dtc's on right now and failed my emissions test today.
Hope someone can help with troubleshooting these codes0102, 0304, 1250, 1569.

Am I looking at an expensive repair or can I do some of this myself. I should note that I had a rat living in my engine over the winter which has made a mess! I think the stinker nibbled on some wires or so it appears. He is gone now.

 

[tweety2300]

P0102 is mass air flow sensor.

P0304 is cylinder 4 misfire

P1250 seems to be fuel preassure regulator

P1569 vtcs issue

I'd start checking wiring none of those are related and highly unlikely all that would go bad at once

 

[tradosaurus]

Start fixing the easiest and cheapest error codes and see if that clears the others.
I would replace Cylinder 4 spark plug and coil pack. If it's been at least 50,000 miles since spark plug change I would change them all.
Then clean the Mass air flow sensor with throttle body cleaner.
Hopefully this solves your problems.