So I noticed that every once in a while when I do a complete stop my 2010 RX-8, the idle will bog down to 750 RPM for about a second and then back to normal 800-900 RPM.

Is this is normal?

 

Yes, typically. Might have a slight vacuum leak.

 

Especially with A/C on, it's common. It's caused by the A/C compressor kicking on.

 

Sorry guys, need some help, been through a bunch of the forrums and searched google, I have a 09 rx8 and when I got about 6k rpm I get gas and oil coming back out through the tb, have already replaced plugs,could,wires,and the maf sensor, reset the ecu cleaned connectors and checked vacuum lines, the only thing i can think of now is the ssv or carbon build up

 

You can start your own thread, you know
It's not any of those things. It sounds like excess blowby, you're looking at a new engine.

Fortunately, an 09 might still be under engine warranty (8 years/100,000 miles) depending of exact date of purchase. Call Mazda.

 

i Know mine idled so low when my compression was low,felt like it was about to stall itself.

 

I guess I'll add my two cents. This is pretty normal with the A/C on as mentioned before. What I did notice was that when my motor mounts were busted this was a lot more pronounced. Car never stalled but it would give every indication it was considering it. After the new mounts everything has been smooth.