power loss and door dimantleing

[Thunderchild]

first. my matiz seems to have less power than a little while ago the spark plugs are ok but is just dosn't seem to have the kik it once had. could this be anything to do with a worn out clutch ?

second. as the car got a bash and the doors r a bit pushed in i wanted to remove the plastic pannel and push them out a bit. this is ok for the front door but the back door panel will not come out because the window handle is holding it down ho do i get the handle off ?