I am getting a P0455 trouble code on my 3.9 Dakota. This lists as evaporative leake large. I am guessing this has something to do with the emissions controlls. Any body have an idea how to start fixing this?

It must have to do with the EGR system. There is that canister that has to be purged every so often when it builds up with whatever it's supposed to trap. You'll probably end up having to change the EGR valve and purging the canister. You should probably let a dealer put it on a scope and do it for you though, I know that's what I would do. If something goes wrong, you can put it on them, whereas if you do it yourself and it messes something up, they won't know where to start.

This may be impossible for you to check but you could see if your gas cap has become damaged (cracked, the rubber o-ring seal damaged, or just plain worn out). A bad gas cap will cause an MIL and codes to set. If that doesn't help, try looking at your EVAP hose harness (try at the canister - tho larger hoses like to split at the ends). Inspect these areas VERY carefully because it is easy to overlook a damaged hose.

It is not related to the EGR system. That code is set many times due to a fuel cap that is loose. disconnect the battery to clear the code, tighten the cap and see if the code comes back. If it does, there is a leak in the evap system.

I got that very same evap code, the problem was the EGR valve. Maybe my truck is just screwing me around...