Hello all,
Looking for some advice on a coldstart issue I'm having with my Evo 8. Upon coldstart (outside temp doesn't matter) the car will idle at 1k rpms, pulling very little vacuum (-7- -9) with around a 18-20 afr and stumbling to stay alive. I'll slightly put my foot on the throttle (maybe 15-16% throttle position) and it'll hold idle just fine and idle will go up like it should for the warmup process. Once the temp gauge first moves, rpms hold at 2k-2500, vacuum to 18+/- and it'll idle normal on its own and continue to warmup. Only on the first start of the day does this happen or if it sets for a very long time during the day. This only starting happening after my last tune when I changed my fuel setup and turbo from stock to ID1050x (have the resistor plugged in), STM's fuel feed and return kit and a Walbro 450 with an AGT52mm. Fuel pressure holds great at around 39psi with vacuum at idle. Absolutely everything else is normal except for the coldstart and roughly the first 3 mins after starting. Car idles normal at 1k rpms after warm. Tuner claims its something mechanical with the car. Not sure where else to look. Car is SD, Remote tuned on 93, no boost leaks, fuel pressure is steady, stock cams, also have swapped out the IACV multiple times with used oem, my current evo 9 oem and some others from ebay. No change.

Thanks.