2006 ML320 CDI have error code 0894

Daughter was complaining car was going into limp mode, unfortunately it had to tow a horsefloat later in the day, I suggested taking it for a few drives and see how frequently it went to limp mode - then put float on (no horse) and see if it did it more frequently etc and see if safe to do trip (200km)

Seemed sort of OK so Decision was made to do the trip (horse had to be transported) and evidently it went into limp mode 3 or 4 times, kangaroo hopped heaps ( severe lurching on starting to move - like a learner driver on a clutch) , and changed itself into neutral once. All reset on a turning off and restarting.

When I got car here I scanned it - Engine had 2511-1 - left EGR positioner signals fault - which it has had in the past but not always - also glow plugs 5 and 6 open circuit (but they have also been in past - just waiting til next fuel and air filter service to do them when cross tube off.

Transmission had 2783 - friction of torque converter lock up too high - I had this in the other 2006 car last year and changed the transmission - but it was behaving differently - also played up for 10,000km)
and also 0894 - implausible gear or too much slip

I cleared codes and took for short run - no issues - only codes were glow plug

Later wife took for longer run - said it was kangaroo hopping - and went into limp mode but reset on restart - I scanned it and had glow plugs - and transmission had 0894 again (no 2783)

I cleared codes and took long test run - lots of hard starts etc on hills etc - got it to start kangaroo hopping - and eventually started in 2nd and would not go up until I re started. On restart would go ok for a bit then did kangaroo hopping (normally on a start on level ground with a medium to hard throttle but not flat out) . Oddly enough the car got stuck in 4th (live data) once and would not change down (even on starting to move) until it was turned off and on again.

the only error is 0894, I thought I would get something more when it got stuck in high gear -

On hard throttle the car seems to behave normally (we have the term here drive it like you stole it) until it gets hotter and goes into limp mode and throws 0894 etc

I am assuming that this is transmission but was wondering if the engine was starving for fuel etc and lurching etc if it would cause the transmission to slip and the 0894 could be the symptom not the cause

Would I get other codes etc if car has had some bad fuel and clogged the fuel filter (but not sure why this would only be when hot), what does a failing electronic throttle do? The only engine code is 5 and 6 glow plug (and occasionally 2511-1 left EGR)

What else causes the car to lurch a lot - without throwing engine codes?

I have not taken the pan off transmission yet to see if it is full of metal. Fuel filter was done about 40,000km ago