I've been trying to figure this one out for a couple of weeks now.
When the engine is not warm/hot, it drives as it should with good power, but when it gets warm, then it loses power when you put a load on it.
The loss of power is accompanied by what sounds like pinging-as if it's running on bad or low-octane gas.
I've been putting 93 octane in it with the same results.
I've changed the ignition coils/wires and plugs.
I also gave it a seafoam treatment last night.

The car has 116k on it and is new to me. The first thing I did was put a new oem catalytic converter/mid pipe/rear o2 sensor in it.

 

Compression is a start. Have that tested.

But even though ignition and your cat seem healthy, check them to make sure...

 

Have a look at this post from the stickies in this subforum:

https://www.rx8club.com/new-member-f...9/#post4543985

 

Would compression be an issue if it makes good power when cold/warm thru the entire rpm range, but doesn't make good power when it's hot and you put a load on it?

 

Check fuel pump, ignition, CAT and compression.

One of those will be it.

And yes it could be compression.

The housings expand more than the rotors when hot, when the seals can no longer adequately bridge that gap, you have compression loss.

Travis

 

Yes, unfortunately.
As the housings heat up they expand, and the seals lose compression.
Our engines will run with bad compression.
What you describe is the classic symptom of a failing engine.
Get the compression checked ASAP and before you spend any more on it.

 

One of the new coils I bought was bad. Replaced and works as it should now.
Found a good vid on checking the ignition coils here ..

 

Did you have any CELs for misfires after you installed your new cat?
If so, you should check it to see if it was damaged.

 

I was totally waiting for him to grab the wires by hand in that video

 

Q on the above..
When the aluminum housings expand, wouldn't the apex seal springs force the apex seals to continue to keep contact?