I need some help please 2006 chevy 2500hd 6.0 ls

I have been battling with this truck for a long time trying to help a friend out he put in a stage 2 summit cam im not sure on the specs but i did the maf and ve tables that went fine it running good making good power but for the life of me i can not make this truck idle my innovate lc2 i was using quit working so i just bought a innovate lm2 trying to get it to work with the vcm scanner with the serial cable i watch the webinar about the lm2 but its not working far as getting into the scanner but no matter what i do to this truck it it showing 15.0 afr i can not figure out how to change the idle air fuel ratio with closed loop disable it was idleing around 13.5 to one like other said to set it at but with closed loop enable it will not idle at 13.5 afr i need some help here my friend is wanting his truck back and i just wanna make it run right many thanks in advance if anyone can help me

First thing that comes to mind is an airleak at a gasket or vacuum line, followed by a missed electrical connection somewhere. The lean condition suggests the former.

If it has a cable throttle there will be an idle screw, use it to increase the idle speed or, if electronic throttle, have your friend hold it on the throttle while you squirt around the gasket areas and throttle body with some engine start or brake cleaner. If there's a change in idle speed it'll indicate it's sucking in air where you squirted and the spray was drawn in and burned in the engine. NOTE, whatever you use, it has to be reasonably flammable to give the rpm change as it's burned, so take care.