which may go to show that it is pointless doing things to the hub bearings without also giving some thought to the freehub body bearings.
there are several things which may cause a freehub to go draggy
1) particles inside. If there is no slack at all in the bearings (normally a good thing) the slightest contamination of the lubricant may cause the freehub not to spin properly.
2) grease drag. If a #2 grease is used and it gets into the freehub body the freewheeling action may go very draggy.
3) lack of lubricant/corrosion. If the hub was serviced because it was going bad inside, and nothing was done to the freehub bearings, they won't have been improved in any way.
4) Badly fitted seals; there is usually a seal or shield that is push-fitted in the freehub body. If this comes loose (not uncommon) or is not a tight fit when refitted (NB the pressed steel variety always need to be re-flared before being refitted, IME) then they can rub and this can cause the freewheeling action to go bad, either directly or because there is debris generated.
5) Poor lubrication. Under certain conditions (eg very sticky lube) the pawls can be dragged round with the moving part of the freehub body and this can cause the freehub to go snatchy. I have even seen brand new hubs that did this. In most cases simply oiling the freehub fixes the problem.
So there are several possible mechanisms but one probable common underlying cause; it is quite likely that insufficient attention was paid to the freehub body itself.
If there are no signs of trouble it is normally sufficient to add oil to the freehub body, work it to make sure that it isn't full of rust or dried grease (look at the oil coming out as you work it, and listen to the mechanism) and then to use enough SFG so that this will over time penetrate the mechanism without causing excessive drag. The result is usually a nice quiet freehub that doesn't go wrong. However if the freehub is bad it will need to be overahuled or replaced.
cheers