So I have the ssv stuck open code now I’ve took the ssv out cleaned it to perfection Yet it’s still giving the code other issues low end power loss and wile driving in second gear it will miss fire at mid range rpm to detail all mods done decat secondary air pump delete with custom straight pipe cold air intake msd ignition wires and all maintenance is current and keep up to date it’s a 2004 rx8 automatic trans

 

Have you checked the vac solenoid that activates the ssv.

 

Did you also replace the spark plugs and ignition coils? Any engine codes besides the misfire and SSV? Recent compression test results? The SSV shouldn't be causing low end power loss.

 

Can you show the custom intake?
These symptoms are consistent with poor MAF reading, which can be caused by poor intake design. Very few intakes are better than the stock one.

And yes definitely keep coils fresh.