Ford Repair: 2003 windstar, catalytic converter, motorcraft parts

Question
My van runs rough at idle and under a load it dose like a bucking thing when it rain it is the worst.sometimes the check engine light comes on sometimes it dosent please help I did have the van checked for codes and it came up p136.

Answer
have you started by replacing the plugs and wires with motorcraft parts ?? Inexpensive, your problem is indicating a cylinder mis-fire. which will result in the code you listed which is for a catalytic converter concern, should the misfires persist- you will need new converters