Okay this is what I did.
Got the timing dialed in... about 2-3 degrees adv TDC.
The idle is around 800 RPM....
When the idle was lower (that is, set around 500-550 rpm, I would always get the code 43 thrown at me)
Now that the idle is boosted up to that, no more errors are being thrown. I had to triple check to be sure, and I have been running the car for 4 days with the new setting. No problems whatsoever.
I suppose the computer doesn't like that cam very much below that idle range.
Anyway, it is running beautifully now. Thought I would pass this along if anyone else has a 2030 cam with a 350....
Or similar mods that I have.
It might help others if they have a similar setup to me. I'm sort of unique in my area, but others may be doing similar to my setup now.
Yeah! No more ECM errors.

 

Still no codes being thrown! OMG! I'm too happy!

 

I also have the 2030 cam and TBI.(hydraulic roller version)
Mine doesn't like idling below 800 either!
Actually seems happiest idling at 800-950, depending on the water temp.
Mine's also a 350.
Good to hear I'm not the only one.
Appreciate your passing along the info.
-Rich-