Nissan Patrol 4x4 (Africa)

Hi All,
I'm having a persistent problem with my 95 4.2 SGL.
Most of the time she runs fine and is even "pretty nippy" (both Graham Cumming and Peter Connan have driven her about 9 months ago) but come to a long uphill, more than a kilometer or so and she starts jerking and spluttering and losing power as though I'm running out of petrol. The odo is currently on 192000km
So far I have:

1. Had the carb stripped, cleaned and reset by Carburetor Ace, a reputable guy here in Durban.
2. Replaced all the flexible fuel hoses (in case they had perished and were drawing in air while not showing any obvious leak)
3. Replaced the fuel pump.
4.Removed and cleaned the fuel tank. The internal strainer was partially blocked and has now been removed. I have 2 in line filters fitted, one near the tank and 1 up front near the carb.
5. Plug leads and spark plugs have been replaced.
6. Coil replaced with a Bosch blue coil. I'm using the Pertronix Ignitor 1762LSCC electronic ignition from Offshore Marine. On their advice the ballast resistor has been bypassed.

Any suggestions for next steps will be greatly appreciated.
Mike

Does sound as if it can be fuel starvation, but there is one more check of the ignition system that may be worth while: when the problem occurs, check how hot the coil is.

If it is getting hot, it could be spark breakdown.

Be careful not to burn yourself.

Mike, maybe adjust the float level so that there is a bit more fuel in the boal. Not sure if you have already checked this

Two little I M H O 's
I assume you still have the NIKKI Carburetor on your car?
(1) There are three 'pipes' going to the carb from a box thingy mounted on the fender .. Get the exact positioning of those from Peter Conan .. I had the same gaga with my GQ in Namibie after our NAMIB trip and had Pupkewitz Nissan in Walvis work on my car .. they had there "expert" working on mu car BUT he messed en mixed up those tree lines. I had a NIGHTMARE trip back home.

(2) Way back I had a Mazda 616 [1600] .. Just after a service it also started playing up and eventually we found that the appy who had serviced the carb had switched the main stage and 2nd stage jets .

Last thought -- Have you checked the exhaust for a baffle box that the innards maybe came loose and at times then "choke" the airflow?
[Manifold gaskets sealing properly ?

Why two inline filters and why one close to carb........?
fuel don't like heat and evaporates ,maybe reroute your fuel lines in the engine compartment away from exhaust and get rid off the second fuel filter

Thanks Guys, I will work through your suggestions.