Looks like it's been a lot if yrs since you posted this but I got same on my stock ACR. FYII've recently got the P1188 code and I've reverted everything back to stock, so PCM is controling boost again. All solenoids are connected. Car drives fine, just like stock as it should since it's stock again. All lines tripple checked, they are hooked up correctly. Checked for boost leaks upto 15psi since stock I dont go above 13psi. Part throttle boost never passes 4-5psi due to stock WGA and PCM controller boost, as it should be. I haven't heard anyone gettin this stock. I know it's common with aftermarket boost control, but that's not the case for me.
Sorry to hijack, but any ideas?