Ford focus throttle engine malfunction and fault codes

Hello,

I have a Ford Focus Estate 2013 Titanium Auto 1596CC Petrol car in the United Kingdom.

My car has been experiencing issues with fault codes relating to the Throttle, where the Engine malfunction light turns on and the car goes into limp mode and limits speed to 10-20 miles per hour. Turning the engine off and back on, the malfunction light clears and the car continues as normal. This is an intermittent issue which comes up every 1-2 months (in summer and winter), and it seems to mostly occur about 5 minutes from the start of a journey, and usually 10 or so seconds after accelerating from a standstill. Typical fault codes are as follows: 

P0172(92) system too rich bank 1, 
P0175(92) system too rich bank 2, 
P2119(17) Throttle actuator control (TAC), throttle valve - range/performance problem, 
P0121(92) Throttle position (TP) switch A / accelerator pedal position (APP) switch A range/performance prloblem, 
P2135(92) - Throttle position (TP) or accelerator pedal position (APP) sensor/switch A/B voltage correlation, 

and most recently the above plus P0221(92) Throttle position (TP) sensor B / accelerator pedal position (APP) sensor B range/performance problem -  despite the throttle body being replaced with an official part in Sep 23 by a local garage to attempt to resolve the issue. The P0121(92) code did not recur though, and seems to have been replaced by the P0221(92) code.

I'm not sure if it's related but mentioning just in case, I also have a U3003(16) fault code about my battery voltage, although I'm aware the battery is probably around 4 or 5 years old if not older, and I need to get a new one soon, although a battery testing device suggests my battery is at the borderline "good" / "check" level.

Anyway to explain further, 2 months after I had the throttle body installed, I had a disappearing coolant issue, where the coolant housing tank was replaced which fixed the issue. Then a few weeks after that, the same engine malfunction and fault codes appeared again, and when I pulled over with the engine still on to read the fault code, a visible coolant leak appeared under the car. I was able to turn the car off and back on, and proceed home. The garage then replaced the spark plugs, core plugs and rocker cover gasket, which seemed to solve the coolant leaking issue. A few weeks after this, when I turned the engine on after it wasn't used for 5 or 6 days (during 0 to 5 degrees celcius average temperatures), it turned on fine but immediately the engine malfunction appeared, and with the same fault codes including the new P0221(92) mentioned above, replacing the usual P0121(92) code. The garage had a look at the new throttle body, fault codes, and performed a series of tests on the throttle and gas pedal and everything seemed fine, including an uneventful test drive. They are not able to work out what the issue could still be and have suggested I speak to a Ford expert. Having gotten the car back, I have driven 2 journeys at least 30-60 minutes in the last few days with no issues.

Does anyone have a similar experience or what might else be at fault?

Thanks