rover 25- misfire on tickover, poor starting, fuel pressure?

hi i have a rover 25 1.4, it has a problem starting, accelerator needed, and on tick over it misfire's-however, raise the revs to 1500rpm an it's silky smooth. i've taken the exhaust manifold off, and when started cylinders 4,3&2 have blue flames firing out, number 2 being slightly faint, and number 1 only fires when revs picked up. i wonder as the feed for fuel rail starts with injector 4, and injector 1 being the last, if it would be low fuel pressure? - i am losing patients now as i've replaced; head gasket set, head bolts, t/belt kit, inlet manifold, coil packs, temp sensors, plugs, injectors, crank sensor, cam sensor,and removed exhaust incase of blockage,