My son's '96 4 liter was blowing codes P0171 and P0174 during inspection in February, unfortunately the CEL does not work.. so it was a bit of a surprise. I had this past summer replaced the EGR and the tube from the EGR valve to the exhaust manifold. I took a bit of advise from another forum and sprayed carb cleaner on the vacuum lines, intake and finally the tube that runs from the intake to the EGR valve.. and the engine started to race... found something... started poking around with a screwdriver and poked through the rusted tube... FOUND the intake leak!!.. for now I sealed the tube with JB-weld and permatex and the truck passed with flying colors!!Does anyone know if I have to remove the intake to replace this tube? ot just unbolt from the EGR valve and pull it out of the intake?