Rx8 was sitting for about a year was turned on every now and the . but now when driven it loses power and shuts off. Could it just need a flush or is it more serious ?

 

wrong forum, btw.

could be any number of things though. ignition coils, spark plugs, fuel pump, fuel filter, or perhaps low compression engine. i'm not very mechanically inclined, but i would start testing these components to see which is the issue. if its not fuel or spark, then you should do a compression test.