I removed the EGR valve today and cleaned out the line that leads from the engine to the valve. It wasn't clogged at all. I reset the computer and within 4 or 5 miles of driving the engine light was back on. Is there anything else I should check before I replace the EGR valve?

Did you verify that the switchover valve is working? This is the valve that sends vacuum to the EGR valve. It is underneath the black plastic cover that is at the front of your valve cover. There are two vacuum hoses that lead out of it, one to the EGR and one to another place that I can't remember right now. These hoses can become brittle and break, which prevents vacuum from going to the EGR valve.

Do a search on this. There is a lot of information on this site on the subject.

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Jonathan

2011 Mazda2
2000 E320 4Matic Wagon
1994 C280 (retired)

Check the line Jon has mentioned..very common..
..but, the first thing you should do when an EGR codes comes up is to test the EGR circuit,
This is easily done with a hand vac pump..With car at idle , you apply vac at the egr valve operating port. If the engine stumbles when you do this test, this veifies the egr is opening and it also verifies the tube is allowing passage to the engine. You also listen for a SNAP closing of the valve when you operate it with hand pump. If the engine does not stumble with this test , you know the valve is not opening or the tube to the engine is blocked.
If this test passes, then you will know the prob. is in the control side [ like the vac line mentioned, the SOV the line goes to, etc. ]