my 83 300SD will kick down into third when going 60 if I floor it, if it stayed in top gear those speeds may be normal, i would look at your tranny shift points/kick down.
R

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83 300SD.......sold
96 integra SE....sold
99 a4 quattro....sold
2001 IS300.......sold
2002 330i.........current.
2004 highlander limited....current.