OK, finishing up my second LS/turbo Holley build and I have some weird stuff going on. Specs are 5.3L cam/springs 7875 turbo 80 lb/hr Deka knock-offs. Anyway, upon 1st start I did a firmware update (went perfectly), took my known good tune from my other car. I changed to 5.3L and a few minor things to base tune. Did all 1st start procedures with zero issues. Started it and it ran like total crap. Was loading up, way rich, etc. I could only keep it running 20-30 seconds at a time. Started monitoring all sensors and found MAP maxed out on 3.5 bar at 352 kPa at idle, hence commanding to 10° of timing and 10:1 AFR. It was an AEM 3.5 bar MAP sensor. So after some searching, I found the AEM MAP sensor would need to be calibrated to HP. I decided to forgo that and bought the Holley 3.5 SS MAP sensor. Now with that sensor installed, it reads 274 kPa when I turn the key on not running, after about 45 seconds to a minute kPa starts dropping slowly to 104 kPa (takes about 2-3 min). If I try to start it still won't go below 104 kPa and if I key it off and back on it goes back to 274 kPa. So I called Holley tech line this afternoon they told me to unplug all sensors, and verify 5 volts on orange MAP sensor which I did. Otherwise they said to send it back as they did have some HPs with a MAP circuit issue. So I guess it's going into the mail tomorrow. Sorry for long winded, just wondering if anyone has had this issue or any suggestions?