2019 Yukon 6.2 Forward Collision System Unavailable and Check Engine Miss on #8 only at Startup

[YukonJohn]

At first start-up, the 2019 Yukon Denali 6.2L w/ 30K will miss, 'Forward Collision System Unavailable' light comes on, then check engine. Error code indicates miss on #8. After warmup and turned off, the problem is gone when restarted. Plug, wire and injector have been changed by GMC techs. Vehicle has been in GMC dealership 3 times for this problem.

Your thoughts and ideas are appreciated. Thanks.

 

[Doubeleive]

have they tried reprogramming the ecm/bcm?, cleaned and checked grounds? how old is the battery? low voltage on these trucks causes all kinds of issue's.