EGR valve won't cause stalling while driving, and it won't affect the tach.
The two symptoms together suggest the crankshaft position sensor or the camshaft position sensor, (distributor pickup) is failing. Unfortunately with no diagnostic fault code related to either of them, you either have to try a new one or use a scanner to view live data during a test-drive. Those sensors will be listed as "present" or "no". You'll see one of them switch to "no" just as the stalling occurs.
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Saturday, May 23rd, 2015 AT 7:03 PM