02 transmission/ tach question

first off I would like to thank those of you who share your knowledge of GP's on here-you've helped a ton. I posted about a month ago about my 02 3.1L gp having a hard shift and was worried about compatible transmissions. The tranny seems to shift great now, but when I'm cruising at 55-60 mph, the tach is reading 2500-2800 rpm's. Doesn't this seem high? It doesn't seem like the accelerator is pushed down any further, and my gas mileage is still fine. Could this be just a bad tach? or possible more tranny problems. thanks again for the help. love this site.

Sounds like your trans is not shifting into OD! You need to verify 4th gear command & rpm with a scanner.

so if there is an overdrive problem, is there an easy fix? Also is it ok to drive without O/D working properly? How long can I drive it like that? thanks

easy fix no. As for driving it put in third. It could last a long time or a short time it just depends on a lot of other things.