A P0402 means the PCM thinks that there is EGR flow at an idle and there shouldnt be. If it idles smoothly the problem is likely the PFE sensor. And yes it just pulls off the tubes.
A P0000 means that the Mass Air Flow has a malfunction. It could be dirty and just need cleaning or it could be one is causing the other. If the engine is running a little rough it's probably the PFE, especially if it surges while at warm idle. If not, clean the MAF, and do a computer reset.
You could reset your computer by disconnecting the battery, letting it sit for about 15 - 20 minutes then hooking it back up and see if it will throw the same codes. If it does, buy a couple parts and install them.