My truck just started having this problem about half an hour ago. After idling for a few seconds the engine starts to shake violently but the engine speed does not slow down and it's not stumbling either. It's pretty scary to watch. If I rev it up it smooths out nicely. I know it's not a fuel delivery problem. Is it possible that the flywheel is somehow out of balance, and if it is how could that happen so suddenly?

is it a 5spd? If it is shut id down and dont drive it anymore. What has happend is your crappy factory dual mass flywheel has gotten out of balance. Means it's time for a clutch. Do not replace with a factory replacement, do not use another dual mass flywheel use a quality aftermarket single piece flywheel. A luk, valeo, or SBc are all quality clutchs. Take a stroll over to www.thedieselstop.com and check out the forums thier. they havea forum just for the 7.3idi with alot of info for ya. Travis

Yes it's a five speed. It definitely seems to be an out of balance condition. I've never experienced anything like this before. So I'm guessing that it is a very bad idea to drive it at all then? I will have to get it to somewhere I can work on it.

Is this the flywheel I need? http://www.lukusa.com/products/index.phtml?page=dmf

Is it possible that the problem is something else? It only does it at idle and no other engine speed.

only at idle? Sounds like an injection problem of some sort. Go over to the TDS and post a ? they will be able to help ya alot more. Travis

I've been searching at The Diesel Stop and the more I read the more I think it is the stupid flywheel. God I don't need this right now. :(

A luk clutch and flywheel setup can be had forr around 500. Travis