'99 windstar tranny problem

I have a '99 windstar and I have had it to several different garages and they all say the same stuff. I drive for a little while and when I stop at a light my drive gear is slips. so I put it in 2nd to go then shift up to drive. I need help knowing what to do with it or what's wrong with this thing

http://www.automotiveforums.com/vbulletin/showthread.php?t=503334
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I suggest you do the described servo repair. Little time and little money, and it may fix your problem.
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My next guess would be the TRS (Transmission digital Range Selector switch ... or some such).