ReneeR33

I recently bought an R33 GTS 1993 model Skyline, On cold starts the revs rise up and down between 1000 and 1500 rpm for the first couple of minutes untill it is at operating temperature, it is also seriously lacking performance, i'm not sure whether it has been serviced properly as i am the first owner in australia. anyone have any ideas with the cold start problem and maybe a checklist to get the engine running properly? thanks