I have no idea what you're doing, but I can't recall having any major problems with tanking as a WAR or a PLD... I don't mark things, because I don't see the point in doing that in dungeons. I get in while throwing a thing at a thing, do some AoE's, and if the DPS are very well geared, I do some extra AoE's for good measure, then I just alter between targets to keep aggro on them, prioritizing the ones getting attacked the most, and I've got myself a smooth run.

I main a DPS, mind, but I do some tanking occasionally if I'm feeling (f)risky.