I have owned this jetta for 5 years and when I purchased it the instrument cluster did not work so I never noticed the unusual high rpms while cruising at 70. Recently I replaced the instrument cluster and noticed that when I was crusing at 70 I was at 4k rpms. I am pretty sure the tach is correct because it idles at the correct rpm. I am planning to go on a long trip (4000 miles) and I am trying to get everything ready and this is the last major problem I still have to address. any suggestions would be apperciated.