Don't get all technical too quickly, look for simple faults first that don't need you to buy any diagnostic gear!
It could be a air leak somewhere in the fuel system allowing air into the system when the car has been sitting. When you turn the key to position 3 (just before starting) you will hear the lift pump in the tank running to pressurise the system. Switch back to 0 then back to 3 again to purge the lines, do it a few times before actually starting to see if it helps. It's also the way you bleed the system when you change the filter.
The plastic fuel filter housing is also a weak point & can crack or develop leaks. Make sure you replace all the o-rings that come with a new filter.
It's easy to let a bit of dirt into the feed line to the injector pump when changing the filter. There is a very fine gauze on the pump where the banjo bolt connection is, it can be cleaned - there are online guides on cleaning it. It happened my last car & it took me ages diagnosing the fault.
It could be a air leak somewhere in the fuel system allowing air into the system when the car has been sitting. When you turn the key to position 3 (just before starting) you will hear the lift pump in the tank running to pressurise the system. Switch back to 0 then back to 3 again to purge the lines, do it a few times before actually starting to see if it helps. It's also the way you bleed the system when you change the filter.
The plastic fuel filter housing is also a weak point & can crack or develop leaks. Make sure you replace all the o-rings that come with a new filter.
It's easy to let a bit of dirt into the feed line to the injector pump when changing the filter. There is a very fine gauze on the pump where the banjo bolt connection is, it can be cleaned - there are online guides on cleaning it. It happened my last car & it took me ages diagnosing the fault.