Idles real high at startup then kicks down after 30 seconds...

High idle on start is normal, so no worries there

the automatic transmission creeps? is that it?
that means the (brakes are dead) or the engine RPM is too fast.
if engine is cold (was it) the RPM can be and will be very high and will creep. so is it cold, the engine , and how cold, was it at time of creep
and what was the engine RPM.

or does e ofline mean off line or really means stalls.
as in, my engine when off line, like printer. or ?
wild guess there.

this is simple, all A./T have a clutch that has a stall speed
if you exceed that, RPM it does creep, that is how the a/T fluid clutch works. That is why say , when you idle a 800 RPM it dont creep
then you advance the throttle (engine rpm rises) there is a point
that car starts to move, this is the stall speed, threshold.
all normal.
this is why the operators guide has you start the engine brakes on
and trans in park then while holding the brake , you shift to drive
and prevent creeping,,,,,

Sounds like the rear pads are worn out, your front brakes are keeping the truck from rolling. You need to have the high rpm checked for that 30-50 seconds as it is called the "cold start routine" and is meant to rev the engine for that time period. There may be an adjustment to keep it from over revving, check the specs for the rpm.

Even if you fix the rear brakes, the stress on the U-joints and differential or transmission is needless and can be fixed by limiting the high rpm in the "cold start cycle".

I realize that fixing yourself & saving money is the way to go

The problem is,that there are lots of hoses,we don't know as you
don't, what the real issues are or if hoses are even a problem

So if you have no back yard mechanic friends, you have to go
to a repair shop.

Check for vacuum leaks and the idle air control solenoid for correct activation .

i have seen this happen in other makes also, that fast idle is controlled by the ecm, if it annoys you talk to the dealer, otherwise its not hurting anythig

replace the tps throtle possion sensor

This sounds like a normal condition.What happens is the cold start emission reduction component monitor(software program in the computer) is running.
Cold Start Emission Reduction Component Monitor
The Cold Start Emission Reduction Component Monitor was introduced for the 2006 MY on vehicles that meet the
LEV-II emission standards. The monitor works by validating the operation of the components of the system
required to achieve the cold start emission reduction strategy, namely retarded spark timing and elevated idle
airflow.
When the CSER strategy is enabled, the idle air control system will request a higher idle rpm, elevating engine
airflow. While this CSER elevated airflow is requested, the low airflow test compares the measured idle airflow from
the MAF sensor to the commanded idle airflow from the idle air control strategy.

Try cleaning the throttle body. Possible idle air control valve problem.

sounds like the idle air control motor is sticking , not sure what engine you have 3.4 litre ?? also you can ck the throttle plate right on top where the throttle cable bracket assembly part of that bracket holds down a vaccum line that has a rubber gromnet that after time leaks causing idle surge , hope this helps