2010 Mitsubishi Lancer TICKING IN ENGINE

I have a ticking that lasts about 2 seconds upon start up after sitting for long period (couple hours), and when driving I hear it at approx. 2500 RPM while shifting through the gears. I took it to mechanic who said timing chain was the cause. So had timing chain, tensioner, water pump replaced. Took it for test drive afterwards and no change to noise issue. They are now stating carbon deposits is the cause and advise I put fuel cleaner in every 2-3 fill ups as well as engine treatment every 3-4 oil changes. This makes me think they don't have a clue as this presents a timing issue, fuel issue and oil issue! I have already paid $910 and would like to know what is causing the problem verse continuing to sink money while they attempt to figure this out.