The engine races when cranked. Does not idle well. RMPs up & dn

1. Vacuum leak: A vacuum leak can cause the idle to drop, making it feel like you are pressing the brake pedal when you shift to 4x4.
2. Throttle position sensor (TPS): The TPS is responsible for sending a signal to the engine management system regarding the position of the throttle. If the TPS is malfunctioning, it can cause the idle to drop and result in a similar feeling as if you were pressing the brake pedal.
3. Transmission: A problem with the transmission can cause the vehicle to feel like it's slipping or dragging, making it feel like your foot is on the brake pedal.
4. Transfer case: If there is an issue with the transfer case, such as low fluid levels or a problem with the shift mechanism, it could result in a similar feeling as if you were pressing the brake pedal when shifting to 4x4.

redux1
after many posts, we see only 1 clue engine
MAF
the 6ve1 engine
that told me what engines. one word, mAF.
if just one MAF (no map)
so all air leaks are slow rpm caused by lean
but if pcm goes in to limp home mode.
it car race, due to loss of IAC controls
the engine does not run like you think
the CMP/Cke sensors,
if they die , the engine dies.
if they misfire, the engine misfires and slows and stalls'

are you using good scan tools real that see all factory codes. p1, p2xxx?
not just fedcodes, p0xxx?

the 3.5v v6 has a MAP and a MAF BOTH.
on some engines like this, the Map is for idle
and the mAF of for fast.
fooling many machanics
dual mode systems,
the MAF sensor is not very accurate at idle
is the reason for the dual mod
so vacuum leaks, I SAY.

all jeeps use a MAP sensor
"speed density system" ways and means.
and all race with air leaks, (aka. vacuum leaks) with full power.
did you scan the PCM first?. that be first in every case.
if not , you work totally blind. (must we?)
no engine stated. (size and fuel matters)
making accurate answers impossible.!

2004 Cherokee, not here, not in USA< on this USA forum.
my guess its really a

"KJ / Since 2002 The Liberty (called Cherokee outside USA, very odd that)"
so to USA readers its a Liberty. for sure.
in what country ive not a clue, nor what engine options
they use THERE.

i have the 2002,and 05 KJ FSM book.
i see the exports have diesels. got diesel?
our KJ have 2.4L or 3.7L engines.
both race , with vacuum leaks.

one leak that can happen (not guessing)
1: throttle plate gunked up and now leaks air, because the throttle can not close fully.
2: ISC stuck open. (idle speed control valve)
3: vacuum hoses cracked, or just fell off.?

and 50 more ways to leak air, huge.. .in the real world.
we pinch hoses and use propane gas to find leaks
or the smoke machine.

A few possibilities:

1. Defective throttle position sensor (TPS);
2. Bad idle bypass circuit or idle circuit solenoid;
3. Cracked intake manifold, throttle body assembly, or bad throttle body gasket (most likely);
4. Serious vacuum leak somewhere.

To find a small vacuum leak, let the engine idle, spray around the vac and induction area with carb cleaner or WD40 and listen for a change in the engine note/speed. This should narrow the search area. Good Luck

high idle can be associated from a vacuum leak in the system- brake booster hose loose---vent hose cracked /broken or not connected. Check for broken gasket from manifold to carby. Check that the vacuum hose for the distributor is connected and not cracked

it is possible the engine to have a vacuum leak,**** air,or the temperature sensor not to work properly and give wrong message to PCM as cold start. clean also the throttle body from any dirt.

Any time your dealing with a 4x4 system the best start is at you front axle. Its primarily a vacuum leak so check to see if the 2 vac lines are hooked up (its good to check the electric connections.). When your 4 wheel drive is engaged and the motors running you should have vacuum at one or both of thee lines depending on if your in 4 hi or low .
If no vacuum at axle check the Vacum switchs(the plug with 4 vac lines) on top of the transfer case it will have 2 feed lines(grey & green) they conect in to the into the vacum harness on back of motor (passanger side). A vacum schematic is normally located on the raditor core support (right under the hood next to hood release)
Hope this helps

I would look for a sticking Idle air control motor. or a vacuum leak under the throttle body

vacuum leak someplace for the low idle problem,Fuel filter clogged, bad fuel, spark plugs need changing,for the cranking problem.