i would remove the egr and just the passage to make sure it is not filled with carbon. common problem. here is some info for you as well.
The linear EGR system consists of a linear EGR valve, the PCM, and its associated wiring. The EGR valve solenoid is controlled directly by the PCM when certain conditions have been met. The PCM contains a diode feedback circuit which dissipates energy when the valve is cycled OFF. When the PCM commands the EGR valve closed, a closed valve position value is learned. If the PCM commands the valve closed and the actual feedback value does not match the learned values, DTC P1404 will set.
Conditions for Setting the DTCImportant:
When the PCM recognizes that the parameters for setting DTC P1404 have been set, the diagnostic software waits until the EGR cycles open 50 percent or greater 4 times and then resets. If after the 3 cycles the actual vs learned is not within the parameters, the DTC will be stored and the MIL, service engine soon, will be commanded ON.Important:
When this DTC sets, functions will be disabled. When repairs are complete, codes must be cleared and the ignition keyed OFF for at least 10 seconds to allow proper operation.
DTC P1404 will set when the actual closed value does not match the learned closed value within 20 seconds if:
RPM is below 5,000 and the actual vs learned is greater than 0.2 volts.
RPM is above 5,000 and the actual vs learned is greater than 0.4 volts.
Check for backed out or damaged terminals.
Check for a stuck open EGR pintle. Inspect the EGR pintle valve bore for carbon or debris and remove. Verify that the pintle moves freely and the return spring forces the pintle closed.
An open in circuit 452 will result in DTC P1404.
A short to ground is circuit 697 will result in a severe rough idle and driveability complaint and set a DTC P1404.
Compare the learned closed pintle position to the actual closed pintle position with the key ON and the engine OFF. If voltage differs more than 0.15 volts, check for backed out, damaged, poor terminal tightness, or an intermittent open in circuits 416 or 1456.