The EVAP system code has absolutely nothing to do with the EGR system. If the dealer charged you for EGR system work for an EVAP system code, they ripped you off
. Things to check for EVAP system codes: 1) Make sure your gas cap seals & you dont smell gasoline vapors anywhere around the truck. You need positive pressure in the tank (zero leaks) for the system to work. 2) EVAP purge soleniod is inop. 3) You have a tubing leak on EVAP system. The system schematic is shown on a label on the underside of the hood. Most of it is located under the rear of the truck above where the under-mounted spare tire is.
Never having done any maintenance on your 4L30E trans could be a problem that cannot be reversed at this point. These transmissions need ATF changes *about* every 3yr/36Kmi. It's possible the problem is just a dirty range switch (external part), you never know!
G/luck
Joel