Electronic throttle only revs to about 1200 rpm's when fully depressed

not told hot or cold engine
the controls for idle are not the same , those 2 modes.
how high is high RPM,.
hot is 800 RPM regulated by PCM + isc idle valve.
cold is controlled by IAC,thermal air control valve.
and runs about 1200 to 2000 rpm,cold
cold in Florida is 1200 cold in ALASKA is 2000.
if the thermostat is bad, stuck open, and 150f coolant temp the RPM will be stuck high all the time
as will huge vacuum air leaks, the MAP sensor sees that and engine screams.
pully connectors is useless as doing so puts he PCM in limp home mode and idle controls are disabled in that mode. limp
there are lots more tests, to do. but my fingers are tired.
get shop to fix it?

Throttle control sensor

Check the engine in neutral/park and depress gas and confirm engine is slow to rev up. If the engine revs in gear and little or no movement have the transmission checked.

this car is likely a drive by wire.(no cable between gas pedal and throttle actuator motor) Some one needs to observe the throttle to see if it advances when the gas is depressed.

The simplest analysis would be the connection to the engine computer with not a simple scan tool but a Chrysler proprietary analyzer to see the interaction of throttle position and engine RPM

Hope this helps?

You need to reset the throttle position sensor.

Throttle sensor, or relay, has it ever got hot? heat ruins throttle sensors.

maybe your throttle is electronic and when you start it opens itself fully and goiing full throttle revs

just about all cars with a computer have a rev limiter so you don't over rev it spinning a engine without a load is more harmful then with one this is normal

This sound like you need to replace your throttle position sensor.

i'am no expert on this car, but i would chk. the T.P.S. (throutle positioning sensor) there also may be carbon build up on throutle butterfly, not letting it close completely when you take your foot off the pedel.