I've had numerous limp mode situations after I installed "sport" cone-shaped air filter. The air resistance was too low via the new sport filter, so turbulence was not right at MAF air sensor on intake hose.
So I had to relocate MAF sensor some 15cm (some 6 inches) downwards by the air intake pipe, away from new air filter and towards turbo intake. Now the sensor is mounted into curved rubber pipe, just at the begining of curve and limp mode is gone.
Another issues I had were after many dusty off-road trips, the same MAF sensor got dirty and had to spray it with dedicated cleaning spray and problems are gone.
Maybe none of those apply to you, but just in case I suggest you get hands on some good MAF sensor cleaning spray, like this one
https://www.amazon.co.uk/CRC-Sensor-Cle ... or+cleaner and give it a shot before trying anything else. Anyways, it will come handy in the future for regular maintenance.