2004 F150 that has about 50,000 miles on it showed a code of P2195. It would idle fine and run well at low speeds, but under load it would bog down and throw the engine check light on. Pulled the plugs and changed them without any problem..still had same symptoms. Read on here about cat problems and took it to the dealer....bad cat on the right side...fixed under warranty....running good now....just a fyi