two cylinders

[spen1104]

my ph1 172 idles fine but when you put it in gear and try to drive it feels like its dropped a cylinder then for no reason at all everything is fine then i change gear and the same thing happens again this has got worse since a cambelt change and the deteriation of my gearbox diff which i being repaired as we speak just wondering if whilst its in if anything else can be done to cure this

 

[sh33n]

Dodgy spark plug?

Dodgy HT Leads?