Thank you for your question, I see you have been waiting a while for an answer and i can only apologise that one the experts working did not pick it earlier.
My name is Steve and I am a fully qualified technician with 30 years experience, I will try and help you.
If not already done so it would be good to get any codes and the data read from the ECU, reading off the data you will be able to see if the various temperature sensors are reading correctly.
One particular sensor which is often overlooked is the cylinder head temperature sensor, this is particularly difficult to access, and although it does not often flag up a code it may be the source of your problem.
another possible reason for the problem may be due to a faulty EGR valve, and this may be sticking at higher air temperatures, this would also give the symptoms you have. If not already done so I would try using a EGR cleaner through the system.
I would also suggest disconnecting the MAF sensor and driving the vehicle to see if the problem disappears, when the MAF is disconnected the ECU sets the parameters to a fixed unit, if the engine does run well with the MAF disconnected it can indicate one of two things, either the MAF is faulty or the information received is conflicting with the information from the other sensors.
As you will appreciate their are quite a possibilities to the problem you have and I have tried to suggest the most likely. I hope this helps and let me apologise again that your question wasn't picked up earlier.
I hope this answers your question and if it does please click accept and rate me. this will allow me to continue.
Even after clicking accept I will be able to answer any further questions.