Need to fit coil springs to Landcruiser 79 series ute (2004)

Check steering & suspension joints if ok check tyres for distortion & wheel balance

the front strut is an outer case that has the coil spring around it and an inner insert which is the king pin and shocky assembly that is attached to the rubber and bearing in the inner guard
to replace , you have to remove the strut from the car then undo the retainer nut that holds the insert in
the insert is a common item and the job can be done inside the hour per side at any accredited front end specialist shop
you will need a front end wheel alignment done after the job
unless you are trained in the procedure , the coil spring will cause injury if not controlled during the procedure

Do youknow how to double clutch,,, try it and if it doesn't ;crunch;, your synchronizer may be out t lunch.

faulty injectors
have the injectors fitted with new tips and recalibrated
if it has a turbo , have it reconditioned

start with a compression test to determine if there is a weak cylinder or imbalance . the stalling could be fuel related... check pressure and change the fuel filter. more info is needed...... lots of vacuum lines and emissions controls, are the all there? is there a vacuum leak somewhere like the intake, pcv, throttle body or plastic tee?

You should replace the temp guage sender unit. First disconnect wire from sender and with a test light connect one end to wire and one to earth turn ignition on and gauge should start at base and slowly work its way up. Faulty sender. If gauge still on full when disconnected from sender then gauge is either stuck and need replacing

its usually a tire balance issue at that speed. also check the front tires for seperation...it ussually appears as a belt break internally in the tire and can be found out by rotating the tire while you have it jacked up off the ground and watch it while its turning by hand

check transfer and transmission oil

don't stress about your springs just undo the shocks and sway bar and keep lifting the car you will unload the spring no tools needed...

I recommend getting a conversion kit, if there is one availiable, and following the installation instructions.