I acquired a little '00 Civic EX that happens to have a D16A6 engine (manual transmission). It runs alright for about two weeks, then it starts having idling issues. The only thing that fixes the idle issue is to reset the ECU.
I believe the OBD2b ECU is interacting poorly with this engine.

I've been thinking an OBD1 ECU might work better. I'm not looking to tune or race, just want it to be reliable.

As far as I can tell, an OBD2b car with an OBD0 engine and OBD1 ECU hasn't been discussed before.

Which OBD1 ECU would work well with this engine? Would it require chipping or programming? Is there a better option I'm overlooking?

 

An obd1 P06 will be the closest ecu that will run it.

 

The ECU doesn't care which engine is in the bay as long as sensor input/outputs make sense.

However, with this particular swap, the OBD2 ECU choices are no good.

Y8 ECU is going to freak out when there's no VTEC related signal.
Y7 ECU needs a 3 wire IAC signal.

So...yes, an OBD1 P06 might be your best choice here. But...your idle problems *may* be due to something else altogether.

 

Just an FYI because it looks like the problem is fixed now.

What was happening is that there was a leak in one of the coolant hoses.
Since the IAC valve is at the highest point of the coolant system, an air pocket would form there and the valve couldn't cool effectively. So it would "overheat" and as a result the idle would be unstable.
(I put overheat in quotes because the overheating didn't seem to cause any lasting damage).

After fixing the coolant leak, I've been driving it for a few weeks with no problems.

 

Yes all sensors need to be there for the obd2b ecu to see and understand and do the math while you drive the car.