Codes P0441 & P0513

My Neon is currently throwing the two codes in the topic title (P0441 and P0513), which according to this (http://www.nology.com/OBD2FaultCodes.htm) are:

P0441 Evaporative Emission Control System Incorrect Purge Flow
P0513 Incorrect Immobilizer Key (“Immobilizer pending SAE J1930 approval)

Any thoughts on what may be wrong and if I should get it checked out? This codes were read from the dash using the on-off-on trick.

the 441 code dealing with the evaporative emisions canister is probably just your gas cap not sealing this is the most common cause of the problem. Take a look at it and see if the seal looks good on your gas cap. If its not that it could be one of the hoses running to the evaporative canister near the gas tank. hope that helps have no idea about the other code

Thanks :). The codes went away awhile ago, now we're just dealing with a misfire.

That misfire is probably your throttle positioning sensor. I had that misfire problem on my 04 neon its an easy fix it costs about 15$.

Thanks :). The codes went away awhile ago, now we're just dealing with a misfire.
When was the last time you changed the spark plugs?

About one week before posting this initially :P. Turned out to be the plug wires, which I skimped on and re-used. The fun part was my mother thinking that I'd mess something up and insisted upon watching me change them out one by one (she couldn't tell a fuel filter from a transmission). She now runs fine, but has a slight tie rod issue. Something about my sister turning into the path of a truck...