engine knocking noise

[cavx5]

hi everyone...still having engine tapping noise when engine goes to low idle after cold start..it makes 3 or 4 tap noises from the drivers side bank under the plastic piece that covers the spark plugs then goes away..will not do it again unless car sits for several hours...had an indie check it out he said it dosent appear to be valve type noise...maybe a timing problem..just wondering if any type of componenet is on the drivers side cylinder bank...i will be taking her in to dealer on tuesday...any help is appreciated...thanks rob..2005 4.4 with 18k miles