Help!

[tweak'e]

Hi!I have a 2009 Nissan Navara D40 DCI ! I just finished doing head gasket on my car.The water pump is new,thermostat is new,radiator is clean but the engine coolant temperature raises when going in high rpm but lowers when going about 2000 rpm.

radiator is clogged up. don't bother cleaning them, just chuck it and fit a new one.
you may also get a clogged heater. not uncommon for an overheated engine to break off all the crap in the block and it winds up clogging radiator and heater.
also its really really rare to have a head gasket go on a diesel.