GQ down on power and idle rough when hot

G'day all
I have a '96 GQ Patrol RD28T that has done just over 300,000km and most of the time it runs sweet but after a long drive when it gets hot it starts idling really rough almost stalling sometimes and the power drops significantly, on hills it seem to die in the ass alot more too again when hot. I did a search and didn't find any help, my dad asked a diesel mechanic at work and he said it sounds to him like its not breathing properly, and a build up of soot in the stock exhaust could be causing it? Any and all help appreciated.
Cheers
Jarrod

Don't know the engines habits personally, why don't ya try servicing the cooling system inside and out and see what happens from there.
could be a cheap fix to your troubles.
Cheers

What kind if smoke do you get when missing white/ black or none? When did you last service the air and fuel filters? When it is hot and running rough try cracking the injector line to each injector one at a time and see if one makes no difference if so the the problem is related to that cyl then you could try swapping injectors around and see if the problem follows it. When you say hot is this overheating or just operating temp? Of overheating also check for blown head gasket bubbles in coolant with the radiator cap off

Cheers mate, what would servicing the cooling system involve doing?
I'm not 100% about smoke colour but I don't think it is blowing excessive amounts of smoke any colour, It doesn't over heat, but give tell you were the temp gauge sits as I need to replace that.
Cheers

Also would pay to check boost pressure and exhaust gas temp x turbo

Yeah that's one thing I want to do is install the gauges to do that.

there's plenty threads - posts on here about flushing cooling systems.
Or you can get it professionally done.
Also have a look at thing like filters these are the obvious first ports of call.
Tony, YNOT has posted a thread on maintance you should check it out.

Will do, thanks mate. Pretty keen on learning how to do my own maintenance I'm only 17 but I know how to do oil, air and fuel filters but that's it, all of which have been changed a recently, My dad and I did them.

Well, you picked a good vehicle as your first car.
A Nissan Patrol.
think thread was " preventive maintance"

now if only I could get my 2 oldest to get rid of the Gm and Tonka cars.
can only live in hope.

Haha Yeah well it's dad's at the moment and he has had her since new and I know she's been taken care of but he wants a new Patrol so he said if I find out what's wrong with her and pay to fix it she is mine :D
Found that thread too was a great help saved it to my PC so I can go back when I need to, very helpful thanks again mate.
They'll come to their senses eventually... Hopefully haha