Codes P0305, P0301 and P0507, misfire?

It seems like you may have a vacuum leak, I have seen the intake manifold crack and create a leak. I assume you have new spark plug, correct? Also, when the spark plugs were out what did they look like, were they all the same color?

P0305 and P0301: These are OBD-II trouble codes for cylinder misfires. P0305 indicates a misfire in cylinder 5, and P0301 indicates a misfire in cylinder 1.

P0507: This code indicates that the idle speed is higher than expected.

You can use this guide when the engine is cold to see if you can find a vacuum leak:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Check out the images (below). Please upload pictures or videos in your response of the problem so we can see what's going on.

Sounds good, on #4 I would do a compression test in case it is low.

Check out this guide:

https://www.2carpros.com/articles/how-to-test-engine-compression

Please go over this guide and get back to us.

Yep, that will do it, I have seen the valve seats fall out the cylinder head or the exhaust valve get burnt due to extreme usage. We need to remove the cylinder head to be sure and fix the problem. The lower ends seem to be pretty good so I don't think it would be the piston rings. How did the engine sound when it was running? Ticking, knocking? Here is how to remove the cylinder head. Check out the images (below). Please upload pictures or videos in your response to the problem so we can see what's going on.

Yep, it sounds like the valve seat fell out of the cylinder head, please look at the post above for instructions on how to remove the cylinder head to confirm.

Yes, if you remove the valve cover one of the valve stems will be slightly lower than the others.

Sorry I don't have a picture.