Hi....I'm new to this forum and new to rx8s. So I have an rx8 2005 semi at. With like 110,000 miles on it. I bought it used. For some reason it is having problems shifting itself when in automatic.....it will get to like 67mph in 3rd and then stay for a minute and then decide to shift. It's weird and I am planning on taking it to a transmission shop but would like to get some thoughts. Thanks guys.

 

Check the transmission fluid level. Is the "AT" light on? Is the check engine light on?

 

That's your best bet after you check the fluid level.

 

At cliffjumper.....I just got it serviced this past weekend. They changed all the fluids, including transmission fluid. Yes the check engine light is one. They did say they are refering me to a different to get a transmission shaft realignment because my car shakes some when backing up or in a stop position.

 

You need to get the code read ASAP. CELs are more important to these cars than others because rotary engines are more easily damaged by catalyst failure and the like.
The shaking issue sounds more like bad motor mount(s), which commonly fail on 8s.