I have done the following with testing driving after each. removed throttle body and cleaned ports all new egr valve, tube, dpfe, hoses and vacuum solenoid. I put the vacuum solenoid on last. When I cleared code and then installed solenoid, it began to run a little rough. Then my wife just drove truck to store and back 35 mph 8 miles round trip and she said it was acting rough as hell shifting hard and like it was going to stall and the check engine light came back on.

So it only started running rough when the new solenoid was put on. It acted smooth before new solenoid. What is going on and what do I need to check or do next?

 

1st thing you need to do is supply information about the vehicle of concern, year/make/model/engine.

From there it gets more complicated.
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2001 f150 4.6l.

 

Diagnostic Trouble Code (DTC) P0401 indicates that Continuous Memory Self-Test has detected insufficient EGR flow.



Possible causes:

• EGR valve stuck closed or iced.
• EGR valve diaphragm leaks.
• EGR valve or flow path restricted.
• EGR vacuum hose off, plugged or leaks.
• VPWR circuit open to EGR Vacuum Regulator (EGR V.R.) solenoid.
• EVR circuit to PCM open.
• EVR circuit to PCM shorted to PWR.
• Differential Pressure Feedback EGR (D.P.F. EGR) sensor pressure hoses both off.
• D.P.F. EGR sensor pressure hoses reversed.
• D.P.F. EGR sensor VREF circuit open.
• Downstream pressure hose off.
• Downstream pressure hose plugged.
• Damaged orifice tube assembly.
• Damaged EGR V.R. solenoid.
• Damaged D.P.F. EGR sensor.
• Damaged PCM

 

Well I just realized the dpfe hoses were backwards... Which may be what caused all this nasty buildup to begin with.

 

You may also want to consider posting technical questions in the 1997 to 2003 F150 forum. You'll get more exposure there.

I'll move it if you'd like.

 

That crud is normal, it's exhaust gases mixed with condensation, they had a huge problem with them all thru the 90's and into the 00's. We use to replace those sensors by the hand full because of it.
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Thanks I'm new to forums and I think I get what u mean. Thank you for moving. This is cool