Ford Repair: EGR Position Sensor, EGR Valve on Taurus, egr valve position, vacuum hose

Question
Hello.  I appreciate your time and expertise.  Okay, here is my problem, which you have probably been asked a million times.  I recently bought a 91 Taurus with a 3.0L and the Check Engine light comes on all the time.  It usually always comes on within 2-5 minutes after I start and drive, cold or warmed up makes no difference.  The light does NOT stay on, rather it comes on for a few minutes, goes off, comes back on, goes off, and keeps doing this.  But it is mostly always on.  I also notice that it has a very rough idle, yet runs extremely smooth ABOVE idle, and while driving.  I checked the codes, and it came up with a 33, which the code reader book said was "EGR Valve not opening properly".  My friend told me how to remove and test it.  We watched the plunger moving with suction (mouth, not vacuum), then cleaned out the gunk, poured water in it, sucked and watched the water pour out.  He said it appears the EGR is doing what it is supposed to do.  Then several auto parts guys said it was more likely the EGR Valve Position Sensor.  They said it can cause rough idle, and can be sending the EGR an incorrect signal.  But, these are parts guys.  Some will tell you anything just to sell you a part.  So, does this sound like my problem?  After checking and cleaning out the EGR, I still get the light coming on, and in fact it is idling rougher AFTER cleaning the gooey carbon buildup out of it!  Wierd.  Please help.  I can deal with the light (put electrical tape over it!), but I can't tolerate the rough idle.  It has gotten worse in just a few days after cleaning out the EGR.  And the 33 code still is the ONLY one to come up.  Thank you so much.

Answer
This could be a sensor issue if the sensor is sending the wrong information, there should be no egr on at idle anyway. If you disconnect the vacuum hose from the egr, does the idle smooth out? Check that hose for vacuum at idle, if it has vacuum at idle then there is a control problem holding the egr open. In most cases a 33 occurs if the egr is NOT opening. If you have vacuum at the egr at idle, it could be the sensor or the vacuum control solenoid.