there is 2 timing chains. one is for the crank timing and the other is cam timing. if you take your valve cover off, theres 2 sprockets on the left side of the engine. each sprocket looks different if i remember correct. one should have a mark that says INT and the other should have one that says EXH or somethin like that. If i remember the INT cam sprocket has a triangle for the marking, and theres 3 colored links on that chain, 2 blue and one pink i think. the 2 blue links should be pretty far apart, one blue link should line up with the Exhaust cam sprocket marking, and the other blue one goes down to a tiny sprocket just a little bit above your oilpan. the pink link lines up with the marking on the intake cam sprocket.
The p0300, check if your spark plugs would be the first thing i would check. are they the correct plugs for the car? then go from there, are you getting spark to the coils?
2008 Silver LS, 2.2L, 18" wheels, Airbox Mod Rockford Fosgate 10s', Stock Deck, 20% Tint, 10k HIDs, Tsudo N-1, Megan Racing Coilovers