1998 Subaru Legacy outback review from North America

Purchased the car at an auction. I knew the head gaskets were blown. After replacing gaskets testing the heads and shaving them. I replaced the water pump thermostat, timing belt etc. After the reassembly the car continued too run hot. Double checked the thermostat, replaced coolant temp sensor, new radiator. Still running hot. I was close to giving up when suddenly the check engine light came on with a po483 code. After the code came up the car stopped overheating. It seems the overheating problem is somehow controled or partially caused by the ECM electrical system. It is running fine now. I will be selling it and will probably never buy another subaru. I am used to working on Toyota cars they come apart easily go together well and usually run fine after the repair. This Subaru is strange to say the least. I cleared the code from the obd system and I will drive the car as little as posible. Is it possible that some strange glitch in the ECM is causing all these problems. I still don't know what this code means.