Hello, I am new to the forums. I am 19 years old and have always dealt with muscle cars until I bought this 2005 Cobalt Lt coupe with a 2.2 Ecotec and manual transmission. It has 175.000 miles on it. The car sounds smooth at idle and on start up, but once you get it at 2,000-3,000 rpm, it starts making a knocking sound that seems to be coming from the top of the engine (while sitting in neutral or driving down the road) and is worse while you rev it. I have never messed with any of these new vehicles but I have read that it has two cams. It sounds almost like a lifter noise. It also had the check engine light on and was read as a misfire. Is the timing off or do I need to replace the timing chain or tensioner? I'm clueless. Thanks in advance!