Low power, sluggish

Actually,
you diagnosed this yourself,
"very hard to get primed up"
So blockage in the fuel line,
or fuel tank line pick up.
Conclusive proof would be in the filter,
I,e, very little fuel in it,
have a look see.

Hi thank you very much for taking your time to respond.

The fuel filter has plenty of diesel in it and fuel lines have been checked and is all OK.

We where wondering if could be the injector's?

Thanks again much appreciated

Faulty injectors present different symptoms,
If I recall there's no fuel pump in the tank on those,
could be wrong but,
I had a Range Rover classic fitted with that engine in the workshop a few years ago,
Very similar symptoms,
So I got a gallon of diesel with a pipe in it and put it in the passengers foot well,
bled it up to the pump then road tested,
ALL faults gone!!
So I gave it a very close eyeball inspection and found the fuel line had a pinch in it.
Try that.
If nothing else it rules out all fuel supply faults.

Thank you that's a great idea I'll give that a go as is clever way to eliminate any fueling problems. Thanks for that much appreciated. I'll defo give it a try, hoping something simple wrong with her..
Thanks again

Apart from the low power sluggish behaviour the jeep seems to be running perfect. Does idle fine and no smoke. Just started when had been driving and stopped her to go into petrol station and when came back out and tried to start she wouldn't start. After a lot of churning and priming she eventually started and was very under powered. it has died whilst driving also, started one morning and made it about 5miles and she died and was a absolute nightmare to prime up, I mean hour or two trying to get her, I ended up turning fuel filter upside down to allow fuel from it to start her then she put rest up herself and trucked on. The following day I got new filter for her but it made zero difference she is still driving the same. I know prior to me owning her she had been in on the recall for injectors and loom but very unsure as the to 'reciept' from it that was in with the documents for her when I purchased the jeep. As it is listed on it for 'harness injector' price and then on the labour side of things it states 'fixed broken clips on harness' 'new injector harness fitted' it also says on the labour part 'new injectors **' parts of reciept are hand written others are typed.. Plus company is southern Ireland but has a northern Ireland mobile number as their only contact number and a southern email address. At the same time it is meant to have had new spark plugs, front bearing and check on ignition barrel and starter as was 'difficult to start' this receipt was dated for early 2014. We purchased it a year after that.

Up until now has been fine though looking back there was the odd occasion where she seemed bit laggy as if driving with slight brake on. There is no lights on on dash, and starts fine at moment,

I don't know what else to add here to give full picture of the issues we ate experiencing.

Thank you again for your time and experience it is greatly appreciated,

Hi. Just wanted to post the FIX in case anyone else is having similar problems with an Isuzu trooper. Have now found the problem and how it can be sorted. I decided after checking many different things to change the oil as it was recommended to me that on these diesel engines the oil needs to be changed every 4500miles to run well with minimal issues. Anyhow as I have never changed the oil I decided now was the time. Also if anyone else is needing to know these are apparently temperamental regards oil type and 0/30 synthetic or 5/30 is recommended. Once I was changing oil I discovered a hole on the intercooler, this is my problem. New intercooler will be got and that should be problems solved.
Thank you again for your help

Make your mind up dude!
spark plugs!
on a 3 litre turbo D!
I'm guessing you mean glow plugs.
Diesels can do some very odd things when it comes to fuel supply.
All your symptoms lead me to start there.
So try the slaved fuel tank and repost when you have a result.
Either way.

I tend to agree with 1/4 drive about the fuel situation.you wont have a scavenge pump in the tank but the problem may be with the filter head itself especially as it takes a while to build up pressure.The problem could be with the injectors i.e losing pressure the only good way to check is with a leak off check if that's possible,