front shimy / shocks

Lately my 99 dually has developed a shimy in the front. At 45 or faster if i hit an expansion joint or a dip in the road it shakes almost uncontrolably from side to side int he steering wheel and the only way to stop it is to slow down to 15mph or slower. it is getting considerablly worse weekly. I had it in the shop today and all the front end parts are tight and most are new and had the alignment redone on it and it is good. any ideas at all on what it could be is greatly appreciated. My buddy that did the alignment at his shop said that he believes shocks will fix it. it rode perfect without them for months then started this so i am lost. I have been meaning to put shocks on the front of my 99 dually for a while now but am so busy in the shop it has been pushed aside. What shocks are you guys running on the front and amy pics of ur setup would be great.

is it bagged, or lowered, stock? I know the first truck I bagged did this horribly w/ brand new shocks. Switched from stones to slams and never had the problem w/ or w/o shocks. I would say if it needs new shocks try that first. More info would help. Whats your set up now?

bagged with re-7s no shocks in the front stock 16s. didnt do this for the first 6 months or so but now is horrible

this seems to be a kind of common problem.. my 2000 did it but not only on my 19's and then with my 22's.. it turned out that once i replaced the idler and pitman arm it fixed it...... talked to several people who have had the same problem and that seemed to fix there issue too...