Recently purchased my 05 v8 Sts check engine was showing Code P0174, bank 2 system lean. Popped the hood and removed plastic cover to find cracked boot right on top, replaced and the code went away. 2 days later (Yesterday) as I’m driving across town it starts idling very rough when stopped but runs fine otherwise. Pop the hood to inspect again no other visual problems but when I rev the engine I can hear it sucking air along the drivers side of the intake manifold. I took it in this morning to get inspected and the mechanic tells me he can’t hear any vacuum leak. And tells me it the timing chain. (Attaching a photo of the inspection) Hoping to get an opinion from someone who has experienced this before as I feel it is just the intake manifold seals but am being told otherwise. I’m no expect when it comes to cars but no dummy either. Any help or information would be highly appreciated.