Speedo on Renault traffic won't work sometimes?

Hey everyone I have a 03 reanault traffic 115,000 on it just changed turbo,clutch and few other little bits stil have some problems firstly, sometimes my speedo just stops workin and I find it's lost some power then when it works it runs ok,second sometimes it just cuts out when I'm driving but then few seconds later starts not a bother??can anyone pls help?fuel filter also fitted 1000 miles ago.thanks!