I had the same problem when I bought my 95 T100 3.4l. I bought another TB from the wreckers and it did the same. So played with them and figured out that there was air leaking in around the butterfly shaft. I took the nut off the end of the shaft and all the rest of the linkage and stuff . Then I got an oring that fit on the shaft and if I remember it kind of fit in a grove in the TB where the shaft enters. I put it together and it still has lots of spring and no bind and now I dont have a hi idle prob. I did this 2 yrs ago and not a problem since. I was thinking of sending my spare TB to Downey and they bore them 3mm for some extra jam . I wonder if they rebore the butterfly shaft hole because they need a new larger flapper???????????? I tried all the other stuff befor the oring fix as well. Ibought my truck with 360000km or 220000mi. Hope this helps.