Ford Repair: f150 egr system, air control valve, 302 v8

Question
I have a 1988 f150 with 302 V8.  It idles roughly, surges, and gets slightly worse fuel economy than I would expect (about 10mpg).  A diagnostic test of the eec returns error code 32 - evp sensor below minimum voltage.  I have replaced the evp sensor and removed and cleaned out the egr valve, which had heavy carbon deposits, but I still get the same code and the idle has not improved.  Also, the engine light will occasionally come on while driving.  This returns a stored trouble code of 41, indicating a lean condition or no HEGO switching.  Don't know if these problems are related.  Have you encountered this problem before and if so what is the best next step to solving it?  Thanks for your time and info

josh

Answer
First, check the wiring and connections between the logic module and the power module.  Clean and re-grease any corroded connectors with dielectric grease and repair any shorts. I suspect this may be the cause of your problems. Second, Clean the throttle body and idle air control valve thoroughly. Instructions are posted in several of my recent posts. This should help your idle. The heavy carbon deposits may have ruined the EGR valve, so consider replacing it. Cleaning the throttle body on your truck in no easy task, due to the dual air intakes, and that the butterfly valve is so far back inside the throttle body.