my renault 1.9 idles rough kangoo on a 2000 plate?

I have put new glow plugs/ecu/air filter/fuel filter the van starts first time runs perfect at high speed ,but when stopping it runs as if firing on only 2 cylinders aso white/blue smoke from ehexhust I have had 4 reconditioned injectors ( tested OK) was told it could be a fault on the vacuum regulator , this van is doing my head in ££££££ please help