My 2002 ford explorer sport trak 4.0 started to run rough at idle so I replaced,plugs, egr valve,& 2 sensors?

Its still running rough, with the check engine ligt on and the OBD2 tester shows "exhaust gas recirculation flow insufficient detected, any suggestions on what up?r|||Check for vacuum leaks on the vacuum line running to the EGR valve and the EGR position sensor|||If your Really Concerned, i suggest you take it to Ford or a Mechanic thats knowledgeable, to get it looked at. Bettetr safe then sorry. Most likley the computer.|||check for vacuum leaks to the egr valve or to the egr valve solenoid