456 Looses Power Slow down light goes on

Ok I hope that someone can assist me with this?
Last week I took the 456 out for a ride, it was running great with the engine light on " bank 1-6" again still drove great until I felt the car loose power and then what felt like one side of the engine loose power, (the light had been on for about 3 weeks maybe 3 drives") soon after the slowdown light came on. I pulled over as the car was limping along, I turned off the engine and let the car sit for 2 minutes, restated and then the car drove fine again still with the "bank 1-6' light on. Now what??

There are only 42k miles on the car I think not the catalytic converter possibly Engine ECU???

Any thoughts on this one?

 

Ok thanks did so but still the check engine light for bank 1-6 is still on. could this be the thermocouple?

 

Also the thermocouple ECU in my car is much like that in the diagram above not like those that are for sale in on line . Those that are for sale are mounted horizontal where is mine seems to be mounted vertically.

 

I guess the next step is to order a thermocouple.
Any idea if you can use the the new type of ECU in the place of the old type?
I will have to see if i can find the part number for my type of ECU.

Thanks again for your help