Coughing and spluttering

[Shagg]

I have a problem... I have an E36 328i Automatic. 1997
I have replaced the coils, plugs for a service… all worked fine apart from an error code faulting O2 sensors, as it had a rough idle so we replaced them, car went ok but still had a slightly rough idle, after a few days the car started to loose performance, now the car has virtually no power once it has warmed up (about 5 min) and is running rich and occasionally spits back through the manifold then it came up with an AMS error, we replaced that and reset the error code, no change! It came up with another AMS error so we put another new on in (OEM), still no change. Runs a little better in sport mode. We have checked for leaks in the inlet side, boot is like new and we have no exhaust leaks.

We have now put back the old O2 sensors… no change… Tried the all 3 AMS sensors (including the original) still no luck.

Could it be the ECU????? (There is no water damage around the ECU)
If so can we just replace the chip?