Feels like there is no power steering, or very stiff when first driving the car for the day. However power steering starts working after the car has been running for 10 to 15 minutes. What could be causing this?

 

do you get any beeping? the thing will beep out error codes if it has any, so if no beeps maybe its a problem on the output side? or with the controller unit itself?
http://foxed.ca/rx7manual/manuals/Tr...ing_System.pdf

 

No beeping.
My thought is it could be a cold solder joint/cracked finger contact on the logic board. Fixing those has cured issues in the past with other electronics in the car.
I am the original owner and the steering has been an issue for quite a long time, which I have just lived with. Just thought I might get a response from someone who has had a similar issue. I have not seen this issue show up in my searches.
Thanks @j9fd3s for your response and attached info.