Need Help 97 Tacoma 2.4 no comm to ECU/ running rich

Hello Everyone
I recently purchased an 97 Tacoma 2.4 standard cab 2wd, approx 100k miles. I thought it was going to be a economical mode of transportation but is becoming expensive due to an ongoing issue. The truck was sitting for several years , occasionally being run but not driven. I was told it needed a cat due to glowing red. I believe that was from running rich.
Since I purchased it the following was replaced:
plugs, rotor, cap , MAF sensor, fuel pump, fuel filter, fuel injectors (made a big difference with accepting throttle), removed the inside of the cat and installed an o2 sensor extender, installed used ecm.
When the CEL comes on it runs rich and no comm to ecu with scanner or jumping out diagnostic plug under the hood. When I can connect to the ECU it shows no history of faults.
I would appreciate any input. I thought there were similar issues on this forum in the past.
Thank You

 

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