Hi. My gf's 2002 Focus ZTW DOHC is making a consistent noise upon start up. I drove it last week and noticed a whining noise from the engine. Yesterday she drove it and now its making a rattling noise, but doesn't sound like a rod knock. After running for 10 seconds, it quiets down, and is there when revved up. I pulled the valve cover, started it up and all valves moved (not recommended due to mess). Belt tensioner replaced two months ago along with alternator and has a/c compressor. What is wrong with it?