hi guys

i have a sierra 2001 1500 , 5.3 bolt ones + milling oil pump + thermostat + PRC dual spring titanium , NGK TR5IX spark plug + MSD plug wires

when my tuner tune my car we faced detention on gear 2 at wot with a full tank it became a less than before , after 3 days i took my car to a dyno to see my numbers here :



they used wideband at rear exhuast my A\F was 13.37

i took it back to my tuner to see what's wrong with it , now my tuner no matter what he does it keep boosting timing it's around 35-36 at wot

the truck was v6 then i swaped it with a 2004 5.3 i send the PCM to near by workshop which we figured out out they put Suburban stock file from 2001 !! could it be related to this ?

thanks in advance guys