'99 2500 6.0 feels like an engine miss

[jd hauler]

My 99 2500 with the 6.0 has recently developed a slight miss, but I think is robbing some power.  It has 58,000 miles now and I wonder if anybody else is having this or has had it and solved it, and what did you do for it? Also, what do the '03 6.0's have over the older ones? , if any, thanks.