DPFE Error 332

1991 Lincoln Town Car, 4.6L - Check Engine error code 332 - says DPFE error. New EGR value and new DPFE sensor; so those are not the problem. Vacuum and hoses are correct. Disconnecting the connector at the EVR Solenoid, Signal 33 and VPWR always measure 12V - they never vary when I move the throttle. No throttle position sensing errors.

My understanding is the voltage across the EVR connector terminals are supposed to vary when you cycle the throttle, but they don't. So, I don't suspect the EVR solenoid.

I checked EVR signal 33 and it is not shorted to ground. What would prevent it from varying voltage on signal 33 when the throttle is moved? In 20 years of working on cars, I never found a bad EEC unless it had other major problems. But, what else would prevent the signal from varying its voltage?

After talking with some mechanics, I am pretty sure the problem is the DPFE pressure differential sensor is getting a bad read due to carbon buildup. Not sure how to clean the carbon buildup, but pretty sure that's the problem.

Additional confirmation that carbon buildup is the likely cause... http://autorepair.about.com/library/faqs/bl267c.htm

I would remove the snorkel throttle assembly, and clean the crap from the back of the intake. Also, there is a pip that goes from the Cats where the 2 rubber hoses meet up. That metal pipe gets clogged real bad with carbon. I would clean it as well.