my 2001 s80 also had same problem: hard starting, after I replaced the fuel pump (in the fuel tank) the problem is gone, before you replace the fuel pump you can try to clean fuel filter first (located below the rear passenger's door). good luck.

I love my S-80 2001 2.9, but now I use lower octane petrol (because the price differ a lot in my country), the engine sounds knocking, I know it is because of different ignition timing between low octane and high octane petrol, low octane petrol need an ealier ignition than hi octane.
Is anybody in ...