My 1997 Mustang(only 94,000 Mi) shift perfectly into 2nd and third but at about 60 miles an hour it vibrates. Just had valve lifter and intake gaskets replaced but it did it before and still does.
After it vibrates a little every thing is fine. Almost sounds or feels like when you
go over pavement that has those strips in the pavement. Has done this for
quite a long time. What is the cause?
Sounds driveline related. Check the balance of the driveshaft, u- joints and motor and trans mounts.
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