P0660 - Intake Manifold Tuning Valve Control Circuit - Open Bank 1
P0403 - Exhaust Gas Recirculation - circuit malfunction
P0406 - Exhaust Gas Recirculation Position Sensor Circuit - High
P2173 - High Air Flow - Large Vacuum Leak
For the first one, check the connectors and wires for the tuning valve. It's possible that they were disturbed while you did the other repairs.
The last three could all be caused by a bad EGR valve that is stuck open. Either from the connection being damaged or getting coolant in it, or just from age. The 3.5 also had a bad habit of the intake manifold cracking and allowing in extra air. So check for a large vacuum leak around the manifold as well.
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Tuesday, March 21st, 2017 AT 10:11 PM