[xeroinfinity]

Welcome to AF !

Could be a few things going on here.
PO507 is the idle control, which to me would indicate the IAC(intake air control) is dirty/plugged up or its bad and not showing a code.
It is located on the right top side of the throttle body(TB).
It can be removed with a torx bit and cleaned with TB cleaner to see if that helps with the idle.
Dont push or turn the end if you remove it.


The surging you described could be the IAC,
though it could also indicate thiers a vacum leak on the intake manifold somewhere.
You might here a whistling noise when the motor is running if its a bigger leak.

Hope that helps !