Friend of mine has a 1988 ford E-50 Econoline 5.6 liter Van.  After reaching 
speeds of 55 mph, the check engine light goes on and off periodically.  He 
wants to know if a defective EGR valve cause the check engine light to come 
on and off?   Any suggestions about this problem would be very helpful,  
Thanks very much.
--- TMail v1.31.4
---------------