I unplugged the maf sensor without taking the neg terminal off the battery, would that cause it to go bad? I just did my spark plugs and my engine is missing and my cel is on. I didnt use platinum, could that be why?

 

Unplugging the MAF sensor without disconnecting the battery wouldn't do anything to ruin the sensor. It could be the plugs, but the easiest way to find out the problem is to hook up to an OBD-II scanner and pull the code to find out what's wrong. Auto Zone will do this for free for you, except if you live in Cali (for some strange reason they don't do it in Cali Auto Zones). If the engine is misfirig, it could be that you used the wrong plugs or that one (or more) of your plug wires isn't fully seated on the plug.

 

Make sure all the coils electrical connectors are plugged in tight and that the coils are fully seated...if they are you might have closed the gap of one of the plugs.

 

AHA! i fixed it, it was a bent pin on one of the coils! it was throwing the p0300 code