Where is the ECU and the test harness located?

 

I know I'm a few months late on this, but I have some ideas... and a 92 Honda Accord... my first suggestion, and this is one that blew my mind, check the actual intake tubes that connect into the intake/filter box. They tend to get bumped when replacing the battery, and if they aren't snug in their fittings will cause exactly that issue. Too much hot air being sucked into the engine, erratic idle, etc. Took me, personally, 5 years to diagnose on my own.