Hello,
As you referred that you face issue after keeping car idle for longer period, thus presuming no issue when you start car in few minutes or few hours
Seems either an issue
> Fuel pressure Regulator,
> Fuel Injector
> or likely the fuel filter been full of dirt
due to which fuel supply is not turning adequate and causing start issue
When you start within few minutes or some time due to fuel already in flow there there may not be an issue and after a long period again faced with same start issue.
May get Fuel Line System inspected along with replacement of Fuel Filter
Should help !!