Loss of power on hills

[kenjj]

Hello All, my first post so I wonder if anyone can help. I have a 2005 Fusion2 1.4 petrol, car is excellent runner except for one hiccup, when I drive up a fairly large hill the car looses power unexpectedly. Even if you drop down the gears (say 3rd to 2nd) it still struggles and then just picks up and is fine again. I have just done a service so new plugs, air filter, oil and filter also changed ht leads and coil pack and fuel filter. Noticed oil on one of the plugs but no misfires and no check engine light, tried checking the clutch bu dropping from 3rd to 2nd on a run and seems fine revs shot up. Any thoughts or suggestions greatly appreciated.