I have a 2007 Pacifica with 50k miles on it. I am experiencing some engine vibration and engine bog when going uphill. I do not live in a hilly area and having the bog when I am going uphill from areas like an underpass/overpass. I have just had all the plugs changed and had a vacuum test that passed. No engine light and no code. Any ideas to what could be causing the bogging?

 

Maybe ignition coils, but I would think that would throw a code. Is it exactly the same now as before you changed the plugs? Maybe low fuel pressure.