Hello and welcome to Justanswer.com my name is Enes I'm a Certified Volvo Car Expert Mechanic.I'm going to try to help you find the help you need .
clutch kit is maybe needed for clutch problem they wear out fast
now for other problem you have you have new glow plugs and still problem
you must test fuel pressure if you are loosing rest pressure like it leaks down thru injector or fuel pump or regulator it can give you long hard start
so they must check again fuel pressure best is if you can use Volvo garage they can test on advanced Volvo scanner the fuel pump output on digital display and than measure it with gauge see if they match
reply here when you online im in usa so is time difference and delay in replys