Car lacking power

If you know how to calibrate the ignition and valve timing afterward probably yes otherwise it will just be noisier.

cranks fast will not start.
fuel path is dead.
do fuel path tests next using tools do you have tools?
filters first. (not packed up)
not bad fuel or full of water.
make sure pump runs and full pressure.
no VIN told or country. got turbo in it.?
no year told.

are not all these cars (pickup/bakkie) in AFRICA
for sure not in USA any KB>

over 20 years one class of car and engine the fuel injections systems evolved RADICALLY.!!

no person can guess your VIN.
the vin tells country year and what drive line is there, that we can NOT GUESS>
veh., IDent number VIN.

lacking that you get generic diesel answers
or worse raw guessing.
best is get a shop to fix it,

The main reason is the car is underpowered for better fuel economy. This model is a gutless wonder, only thing worse is a Smart for 2 car.

do you have mil light on?

Have you checked the PCV system?? If its stuck in the closed position then you will lack power and turbo boost. A vehicle needs 3 things to make it run proper; FUEL,FIRE and AIR. Try that and see if it helps.

use a fuel additive to clean fuel lines and injectors,redexe/wynns,one can to 1/2 tank fuel.then see if you need to do any other work.....

It is not really possible to "disconnect" a turbo. Its bolted to the exhaust manifold and all the exhaust gas is routed through it. you would have to try to find a header or exhaust manifold the was built for that car and not designed to run the turbo. Even if you were able to do this you would still have to have someone advance the timing back to where it should be for a natuarlly aspirated engine and re program the computer / change fuel enjector sizes to get the air fuel ratio back to ideal. (running without the turbo would cause your engine to run rich with fuel and cause engine fouling problems not to mention poor fuel economy.)

Have you changed the spark plugs and fuel filter yet?

One of your turbo boots or intake boots is off or has a hole in it! Could be either cracked or has come loose of the clamp. This is your hissing noise your hearing. It means the turbo is making the boost but it is not getting to your engine. Its leaking out the boot. No boost no power! Poor performance and bad fuel economy too. You need to check all of your boots and clamps. If you say it is by the firewall then start on the side that the hiss seems to be comming from. DONT unplug your turbo waste gate as you can damage your turbo or other engine components! your waste gate allows excess pressure not needed on your exhaust side to escape.

sounds like air flow meter