So I have had my 06 rx-8 for about a year now and I haven't had any problems with it untill about 2 months ago. When I drive my car and get on the highway and try and stomp on it in any gear it will go untill about 5 grand then it just makes this bogging gross noise and i have no power sometimes I can barely make it up hills on the highway even downshifting into 3rd, it seems like when my car is under prussure it can't handle it I Have no power in higher rpm's. So I took it too the dealer they said the cat was clogged so after 2 months waiting for a new cat they finnaly put it in and it still runs the same and I know its not the cat any more because i just ran stright pipe but the problem still happenes, any boday got any ideas I need your help, maybe fuel filter?plugs? i don't know I hope someone can help me out

 

I'm no mechanic.......but sounds like ignition coils.
search on here and you'll find lots in regards to the above.
Hard to believe the mechanic would not have diagnosed this problem before giving you a new cat.

 

power loss tsb? cat or coil most likely could also be a clogged secondary injector. all really easy things.

 

I have had so many problems with the dealer and trying too get them too fix the problems with my car last week I had my car in 3 times it's just getting too be a hassel my car still has tons of warranty I have under 60000km's