Sametal

So I have a 2008 XLT and I believe I am having either a timing chain tensioner issue or maybe the phasers or maybe everything issue. So basically the truck starts and runs great while cold but after driving a while and the truck gets warmed up and pull into a parking lot, I can barely rev the motor to 600-700 RPMs and let off the gas and the motor starts to knock and acts like it's going to die. I actually found a youtube video of the exact sound I am having, but since I am tight on money and will have to have it done somewhere I'd like to get this forum's opinion on what it might be and maybe a possible cost for a fix. No check engine light either. Thanks!

(First 10 seconds of this video)