nissanrules

Hello. I was wandering what the resolution was. I have a 2003 Pathy with a K&N air intake system (or fuel injection kit as they call it now). I bought my pathy used and it always has a low idle (between 600-700), but I recently had a car alarm installation which triggered a chain of events that included me having to replace the ECM, APP (Accelerator Pedal Position sensor) - nifty little sensor attached to the gas pedal. Now it shuts off as soon as I start it. To keep it running I have to give it a little gas as soon as I start it. I have replaced also replaced the MAF. The dealer reprogrammed the new ECM and got stuck on the idle learning. The system just will not idle high enough. I have a code reader so after I drove it home, the new code that came up is P0506 (the kicker ---the check engine light is not on). I am wondering if the PVC valve is bad, but it's hard to get to. I have also read that the throttle body could be bad (the 2003 pathfinders have a sensor driven throttle body --no cable connection from the gas pedal to the throttle body like in older cars). So, if you have any new information. That would get great. Thanks!