SES Light - P0404, P1400, P1404 errors

My SES light on my 99 Tahoe came on about 400 miles ago (while on vacation of course) and after stopping by an Auto Zone, I have 3 error messages, P0404, P1400, P1404. They are telling me I need an EGR valve. The car is starting to idle rough and I was wondering if others feel the EGR will fix the problem or am I in for bigger problems that an ASE mechanic will need to handle?

Thanks in advance for your time.

Try removing the egr and cleaning it up with some throttle body cleaner and check the engine ports for carbon build up

With the P0404 (Egr Open performance) and a P1404 (Egr closed performance) codes, I would remove the EGR valve and inspect.
Most likely with those codes and a rough idle condition, the valve is stuck open..most likely from a mechanical failure of the valve (carbon deposits are not common in that engine)
You can replace the valve yourself.