I have a 2003 Tracker 2L w/41,000 miles. I just bought it and changed out the spark plugs... While listening to the engine in the garage, I started to hear a slight knocking/rattling coming from the belt area after it was running for about 2 min and warming up.... after it warmed up and the rpms dropped to about 700 to 800 it went away... I added some gas and at around 1000 to 1100 rpms it started again... as the rpms go above 1100 it also goes away.... any ideas??????

 

pull the valve cover off and check your chain guide at the top of the chain between the cams, they are known to break off and then bounce around on the chain. It will eventually get the chain and cam gears chewed up and hurt your engine