I have a 2008 6.7 diesel Ram 3500 with 28000 miles. Since it had 500 miles I have had it at the Dodge dealer several times for surging and chugging. They cannot fix it. They have replaced the torque converter and replaced the fuel injector wiring harness. The problem seems to happen on a flat grade or downgrade. It does not happen under acceleration. The Service Manager tells me the fuel pressure is normal. Any ideas from you I could pass along to the dealer mechanics? PS, The check engine light problem seems to have been corrected after two "flashes".
Well, after 10 days loss of the vehicle and another torque converter paid for by Chrysler, the same problem exists. Would drive line backlash have anything to do with the surging, chugging? The problem can be felt in the seats and is like two or three quick misses of the engine. Again the condition only happens when driving 55 mph on a flat surface or minor downgrade.

 

Do you have any mods or are you running completely stock? If you fill out your signature, we won't have to ask

 

Completely stock. At this reply, the dealer is installing a second replacement torque converter.