Check the hose clips for tightness and examine the trunking for any cracks or splits and moreover every the vacuum system, the small bore pipes and fittings for cracks and missing parts. The best artifice to find a leak is to have the engine organization and warm and later spray lighter gas /propane or brake cleaner roughly each joint in turn. If the engine rev s going on you ve found your leak.
Its also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a not a hundred percent pump will every consequences in insufficient fuel mammal delivered to the engine. Might next be worth cleaning out the idle zeal govern motor / valve as these acquire clogged occurring similar to carbon and some brake cleaner washed through helps free things off.
I don't have any check engine lights unless I unplug the MAF sensor. similar to the MAF is plugged in then the car will stall unless I put my foot upon the accelerator. There is after that an intermittent popping hermetically sealed coming at idle.