2004 explorer (lights, heating and gear slamming issues)

[Nothing_but_Ford]

:scratch::scratch::scratch:
as stated I have a 2004 xlt 4.0 V6 explorer
the problems im having is as listed
* dash lights stay on: abs,, wrench,, brake,, service engine soon..
my 4x4 lights periodically flashes on and off..
* my transmission: slamming into gear at times,, slipping going uphill (at least 70% of the time),,,and feels like it hesitates as well..
* its not throwing heat (more like very luke warm) what I've done so far:
flushed radiator, heater core,, changed the heater valve actuator and my blend door needed replaced
I bought it used around 3 years ago so im unsure of the upkeep on it
I have a apt for a full tranny flush (drop pan, screen replaced,, torque converter flushed)
the codes are popping up the throttle position sensor and that's in the works in getting replaced as well
people are coming up to me saying that the sensor could be the culprit to my transmission issues too..
any thoughts on these 2 (heating and transmission) issues or should I start looking into some other means