[v8volvo]

How much smoke during cranking and after starting? More than before, or less? Rough running for the first couple minutes after a cold start? Minimal smoke during cranking before starting and fairly smooth running after startup is a likely sign of air ingress into the fuel system. Lots of smoke and poor running during and after starting points to incorrect (retarded) injection timing.

I second Mike's advice to absolutely avoid any kind of starting fluid. What kind of shop did the replacement? Do they have any VW diesel experience or tools? It sounds as though they have got the timing off as well as the belt too tight. Special timing tools (dial indicator and holder) are ***REQUIRED*** (not suggested, not highly recommended, but absolutely required) to set injection timing on any mechanical VW/Audi/Volvo diesel engine. Working without the proper tools, information, and techniques means you are shooting in the dark on timing, and are almost guaranteed to achieve an incorrect result that causes difficult starting, loss of power, reduced fuel mileage, excessive smoke, rough running, accelerated engine wear, and a litany of other problems.

It is a very easy task to do with the proper tools, which are available inexpensively on ebay. All the necessary info is available here. You could do the timing and belt tension adjustment yourself in a weekend afternoon, or a good diesel-familiar mechanic willing to learn a few new tricks (some are not!) and supplied with the appropriate information and tools could also do it without any trouble. Just to check the timing takes about 15 minutes with the dial tool; adjusting it takes a little longer but is quite straightforward once you understand what needs to be done.

If the fuel pump is leaking air in, that can be temporarily solved with a low-pressure electric helper pump in the fuel line. Even just installing a hand primer bulb in line before the fuel filter can help identify that issue; if putting one on and giving it several squeezes before attempting to start makes it start better, then you have an air leak. Proper fix is replacing the relevant pump seals, but my money is more on timing than fuel leakage. Generally with a leaky shaft seal, air leaks in when running but fuel leaks out when sitting overnight, so if that is your problem you should be able to see/smell evidence of fuel leakage from the rear of the engine. If everything is dry then you are focused on timing or perhaps glow plug issues... but unless you know for sure that your mechanic had the ability and equipment and inclination to set the timing right and did so, I would start there.