When did FORD improve 4.6/5.4 heads?
Was it '01 model year that FORD improved cylinder heads on Econoline 4.6/5.4 motors in response to complaints about spark plugs blowing out?
Tried Search, but results didn't seem to have anything in common w/my key words or each other. Didn't have patience to pour thru all the pages. Don't know how to restrict Search to 1968 - Present Full Size Vans.