Hi,
2014 Doge Grand Caravan - 127000 km = 80K miles

I'm wondering what the normal temperature range is for the air intake sensor?
I'm using a bluetooth OBD+ sensor and app to gather data and it shows air intake temperature of 50 degrees celcius (122 farenheit) or sometimes 38-45 degress celcius (100 - 114 In Farenheit),
Outside temp is 21 degrees celcius. - 70 degrees farenheit

I'm dealing bad City Driving gas mileage (11.7mpg or 20L/100km) and trying to source the cause. No engine error codes, scan using an app doesn't show any issues. I've changed the spark plugs, air filter, Map sensor. I've used some Lucas Sea foam fuel injector treatment.

Repair shop tested the vehicle and said everything is working to normal standards but I think they only highway tested it.
Repair shop says its because of the weight of the camping bed and mattress in the back.

Any thoughts?
Thanks in advance.

Mark