Can you get any codes out of the ECUs? Iirc there is a screw/light on it...but its been awhile since I had an rb20.

What you just described sounds like what my car was doing last week. The ground for the MAF was bad inside the ECU. I tested the wire from plug to plug and it tested good. ECU had grounds, power. So I grounded the MAF at the sensor side harness plug, fixed it right up..

Ive seen the same thing happen on a couple Mitsubishi ECUs and now a KA so I figure Id mention it..