I'd posted a while back about a '90 244 with the check engine light on. I got 213 and 231. Checked the throttle switch and wiring, verified that to be good. Problem turned out to be with the ECU itself, swapped in a known good one from another car and all the problems went away.
Experience has shown it to be extremely rare for ECUs to fail, I'd only ever had to fix one once, a Bosch in an old VW that had a shorted capacitor in the power supply, but now I read that LH 2.4 boxes are failing fairly often and the salvage yards are picked clean. The LH 2.4 uses one of those stupid ceramic thin film hybrid modules which is effectively impossible to repair, and go figure that's where the issue seems to be. I can trace the TPS signal into that and that's where it ends. Don't suppose anyone has ever reverse engineered one? ECU info seems to be very hard to come by. I may draw up a schematic of the dead one, but the hybrid module is a tough one, two IC dies on it that obviously would be very difficult to identify. I fixed a 2.2 ECU recently that was my own fault for plugging the AIC valve connector into the TPS of a 740, they are entirely standard off the shelf components, so not likely to run into this sort of issue.