irratic idleing +missfire

hi, anybody help.freelander 1.8 petrol injection on 1998 suffering from irractic idleing-1100-1300rmp generally.rising to 2200 rpm after stopping at junctions ect. a quick blip of the throttle will bring it down.only to rise after a run again. also appears to missfire on a run .intermittant fault.changed plugs leads dissi.cap +rota arm any suggestions ,ta.

ok, first of all what vehicle is it and secondly if you post it in the said vehicle category you will get a better responce , welcome to the mad house matey