A turbo 617 runs very well when it is running correctly. Yours is not.
A few things to check:
1) Air cleaner.... is it plugged? I have seen them covered in oil from too much blowby. I have seen
them completely packed full with dog/cat food
from rodents!
2) With the engine off!  Remove the black plastic U tube in front of the air cleaner. Reach in the
front of the turbo, you can use a finger, and see if the turbo spins freely. It should.
3) Look at the back end of the intake manifold. You will see a banjo bolt and a white nylon tube.
Follow it from the banjo bolt across the firewall ti the switchover valve by the brake booster. Is
it broken any where?
4) Now follow the other hose that comes out of the switchover valve to the enrichment diaphragm on
the top of the injection pump. Is it broken any where? Or even connected? If yes, OK.
5) Get a 12mm wrench and remove the banjo bolt on the end on the intake. Careful, don't loose the 2
seal washers. With the bolt out, you will see that it is a hollow screw. Boost pressure pressurizes
the intake, boost pressure goes thru the banjo bolt, thru the tube, thru the normally open
switchover and pushes down on the top of the the enrichment diaphragm. Is the bolt plugged with
crap?
If yes, clean it out.
If no, remove the end of the tube from the enrichment unit. Try to blow thru the tube from the
enrichment unit end. Can you?  It should be wide open all the way to the intake.
If no, remove the long tube end from the switchover valve. Blow thru the enrichment unit end. Can
you? [see b below]
If no, the switchover valve is plugged with crap.
If yes, blow thru the tube from the end of the switchover valve to the banjo fitting. If no, it is
plugged. Get a new hose from your dealer.
b from above: If yes, you can blow thru the tubing from the enrichment end to the banjo fitting with
no problems. Turn the key on. Look on top of the intake for the single wire pressure switch. While
holding the switchover valve with one hand, unplug it and plug it back in. Does the switchover valve
click in your hand? If yes, the pressure switch is bad.

With all the tubing wide open and clear, drive the car. You should feel fuel enrichment come in at
about 15 mph with the turbo boost.

OK, fair enough, you're serious about some DIY. Welcome.

A compression test will tell the internal condition of a diesel. Since
you already own the car remember this for the next one.

Hard start: On the left fender is a black box with wires going over to
the engine's glow plugs. Slide the plastic cover UP - under it is a
"fusable link" or 80 amp fuse. If it's broken you need to replace it for
the glow plugs are NOT working and the engine won't start in cold
weather without them. The link costs about $2 at a dealer.

Acceleration: Karl told you how to clean and check the ALDA circuit. Do
that. Then note how the transmission shifts. If it shifts up too soon
the engine can't reach its (120 HP) power range and needs an adjustment.
That may be the problem.

This car has a 0 - 60 time of about 13 seconds - when its in good shape.
That's the goal.

This old car has been neglected so you need to correct that deferred
maintenance. A diesel is a simple engine that needs lots of air, some
fuel and good compression to run well. The engine's air filter ought to
be clean as should its two fuel filters - the small clear plastic one
and a spin on can up near the valve cover. If the engine stinks of fuel
the "bleed off lines" between the injectors ought to be replaced - buy
4' of "bleed off hose" and cut the old hoses off using a utility knife,
one at a time, and replace them. The short stub on #5 cylinder has a
steel plug - push the plug into the replacement stub hose BEFORE pushing
the hose onto the injector's barb.

This engine has mechanical valves - that means they need to be adjusted
every 15K miles or the engine will lack power and have hard starting -
for lack of compression. This adjustment can be a DIY job for an owner
who's patient and careful. I can send you directions if you're interested.

Noise in front end. Could be dangerous - ball joints, tie rods, or not -
stabilizer bar bushing. It needs to be checked and fixed. It could be
due to bad idler arm bushings - as could the poor steering response.
Look down the right side of the engine to the idler arm while someone
turns the steering wheel from side to side while you observe the idler
arm. If it lifts rather than pushes the right wheel its bushings are
worn - a $30 idler arm bushing kit will fix that. Play could also be due
to a bad steering coupling - look at the coupling just above the
steering box. Turn the wheel - is there play in the coupling. If so,
replace it. On the steering box you'll see what appears to be an
adjustment. At this point DON'T. Fix everything else first.

Any questions?