fiat fiorino ?

have a fiat fiorino 1.7d 1997.

i have replaced the glowplugs and checked them to see if the were working before putting each one back in.

I have also replaced the wire to the plugs as it was a bit tatty with slits in the insulation.

but i still cant get it to start.

i have to be tow started it in second gear and at first the engine turns over but doesnt respond to any accelaration. then if a put the clutch in and do it again it turns over and responds.

once its been started it turns over for the rest of the day sometimes it still wont turn back over.

it drives ok and is responsive

can any one help