backfires and sometimes dies *searched*

[nismo tuned s14]

ok...ive disconnected the bov and it still does it. ive put the timing in every position possible. ive check some of the vacuum lines. my plugs are 2 degrees colder than stock. theyre gapped properly. i dont have any egr leaks or exhaust leak. im using the stock fpr with a walbro. any ideas why its still dying when i come to a stop? it sounds like unused fuel. the idle is slightly rough but barely enough to notice. when i downshift its not smooth, like something to do with not using all the fuel. maybe i need to change my cap and rotor? ive tried everything i could think of and everything the chiltons manual says. but obviously the chiltons manual doesnt have turbo stuff in it.