No acceleration 3.2 DID Gen4 Automatic

[OBELIX123]

in Automatic mode (D) when accelerating , no engine response but no lights coming on either.
After changing to MANUAL and selecting appropriate gear according to my speed car accelerates normally and when changing back to AUTOMATIC while driving, everything works normally with acceleration and deceleration....until next time.
I must add we were driving on the M! yesterday at 34 degrees and it was in peak traffic !(17;30 +++)
with max speed of 20 km/h and constantly slowing/speeding up etc etc for about 1 hour and of course A/C on.
No instrument light came on and water temp was normal as usual.
Once we left the heavy traffic and could drive at least more normal and in fairly good city and suburban traffic we had no problem again.
I am not sure whether this was perhaps heat related (Diesel pump, air lock in fuel line ?) or gearbox or engine management control ???
NO instrument panel light(s) at all came on during the experience , so I am wondering whether it might have been fuel or air supply to engine,
I had the Turbo checked about 6 weeks ago via a pressure test with engine (and Turbo) running with revs and pressure was very normal (I was worried about a possible blockage of the Turbo feeder pipe which can cause Turbo destruction )....
Has anyone had a similar experience or an idea what could be the cause ???

[Majluck Inc]

Hi am here to help have you done a cross check on your TCM with your ECM for trouble codes on with your diagnostic machine, check with the throttle and your balometric sensor or MAF sensor as well and lastly check on the fuel spill valve on the Sp3 pump and the sensor on the common rail as well.