I have a 2004 4 wd automatic 3500 diesel with 170K miles. A short time ago I started having a problem. When at a light, idling, I give it fuel to go it acts like its flooded and won't go. If I put it in neutral and depress the peddle a couple of time it revs up and I can put it in gear and go. If I put it in neutral when I come up to a light and then back in gear when I get the green lights its fine. The other side is if I'm in traffic and going real slow it does it constantly. I just replaced the fuel separator filter thinking it might be part of the problem, haven't done it in way too long, didn't help. The check engine light comes on, haven't had time to put a scanner on it. Anyone herd of this before? Any ideas where to start?