HI, I am new to forum. Did my research here on the P0401 and this is what I have done:
1. Changed DPFE Sensor and hoses
2. Changed EGR Valve
3. Took of throttle body and cleaned EGR ports (were not bad but cleaned anyways)
4. Change EGR Vacuum Solenoid
5. Took off EGR pipe and cleaned with cleaner and made sure air flowed throw all pipes if cover other ends and they did

Still getting P0401 code and truck still running rough, gas mileage sucks. I reset the codes with reader every step. I don't know what else to look. Any suggestions and help will be appreciated.

 

Do this next.
Remove the hose from the EGR valve and plug it with something.
See if the motor smooth's out.
If yes, the EGR is getting vacuum when it should not.
Check that both hoses are on the DPFE correctly. They are two different sizes.
If all ok, check out the hose to the vacuum reservoir in the passenger side fender well.
Some place in this hardware line up is the issue.
Good luck.

 

The hoses on the dpfe are correct. That was the first thing I check once I replaced all the EGR system parts.

Should I plug the hose when the truck is warm or cold?

Where is the vacuum reservoir? What do I need to take off to see it?

Thanks for your help in advance.

 

Can someone help me please?

 

Have you done what I suggested?
We need to get some info to work with.
Remove an plug the EGR Vac line. It makes no difference is the motor is cold or hot for this test.
What result do you see from this test?
Good luck.