Hello, I just completed a swap on my 2001 Camry. The car is originally the 4cyl 5sfe and I swapped it for one out of a 1998 Camry. The engine that I removed from my 2001 overheated and died according to the previous owner. It was locked up, so I swapped it for one out of a 1998 that had lower miles. I swapped over the engine/transmission combo.

I installed all of the 2001 intake manifold/sensors/etc. on the 98 engine. So the only original stuff from the 98 engine is the head and block, everything else including accessories are all from the 2001. I did that assuming that the 2001 ECU would work because it came in the car.

Fast forward, I got the car to run and actually idle for a good two weeks while sorting things out. I later found that the IACV needed to be cleaned (No CEL at all), so I did that and reinstalled. It seemed to idle better for a few weeks and then started dying out as soon as I would give it fuel. Now what it is doing is idling high (1500-2000rpms) for about 15-30 seconds, and then it will stall on its own. When I press the gas to keep it running, it will just stumble and then stall again. I've replaced the fuel filter and the fuel pump seems to operating fine (but admittedly I have not replaced it. The best I can figure right now is that maybe there is a possible ECU issue, but I'm clearly stumped.

Does anyone have any experience swapping these engines from different model years? If so, what can you make of this so far?

I can certainly add more detail where needed. Any help is greatly appreciated.