Cannot identify leaking vacuum hose.

the service manual OEM 120 pages, said this, did VECI fall off?
VACUUM SCHEMATICS
A vacuum schematic for emission related items can
be found on the Vehicle Emission Control Informa-
tion (VECI) label. For label location, refer to Vehicle
Emission Control Information (VECI) Label" << federal laws here EPA.


engine starts (sure) but does it have FULL POWER hot and cold????????????
throttle cable jammed?
is it automatic tranny>? and Kick down cable jammed?
got cruise. and cruise to TB cable jammed.
scans show this:
"P1299 Vacuum Leak Found (IAC Fully
Seated)
MAP Sensor signal does not correlate to Throttle Position
Sensor signal. Possible vacuum leak!"



FAST IDLE HAS MEANY CAUSES!
THE Primary case is the IAC fails or vacuum leaks cause the IAC to go out of control. IAC is bolted to the TB. and is weak, then.

I have the service manual, so can be exacting
as you may know this jeep uses MAP Sensors fuel then engine.
called Speed Density system. jeep (as in NO MAF sensor)
that means any vacuum leak, cause fast RPM even your right foot does.
the 2.5 is cut down 4.0L:
and is MPI 4 injectors injecting it.
we can pinch all vacuum lines, (not PCV) and see if RPM hot drops from 2k to 800 rpm,. bingo that line leaks if it drops RPM large.
easy no? ,just pinch a line. or pull the end point and cork it, up.
the car is 1999 and all 99 cars USA (is it) have OBD2 port. why not just scan the PCM first.? see errors called DTC. and can really help cut down time. and buying useless parts not needed at all.
I owned for years a 1999 cherokee, 4.0L near same drive line. 5sp,m/t box.

here are some very very common caused, seen on all ;my jeeps back to 1988.
this is not guess, it is all jeeps fail here. every one,owned long enough and not serviced correctly
THE IAC is simply clogged up., so clean it? all; mine loved to clog until my newer jeeps are TBW,throttle by wire. no IAC , now, gone.

The the Throttle body TV throttle valve plate is gunked up and sticking open
again, clean it. (PULL TB off)

that is 2 thing things and to be frank , vast places go get vacuum leaks
even old cracked injector cushion seals( at base) sucking air.
we use a smoke machine on the hard nut cases. just like EVAP side.


more, Brake booster leaks, called a huge vacuum leaks
I bet EVAP hoses do not race the engine ever.
map vac hose cracked
egr hoses cracked. vac.
HVAC dash heater controls vac hose cracked and sucking air./
canister evap purge valve hose cracked, sucking air
it has a distributor vacuum advance hose. plug them to see if they leak.
the map sensor quote SM.
"INSTALLATION
(1) Install rubber L-shaped fitting to MAP sensor.
(2) Position sensor to throttle body while guiding
rubber fitting over throttle body vacuum nipple.
(3) Install MAP sensor mounting bolts (screws).
Tighten screws to 3 N·m (25 in. lbs.) torque.
(4) Install air cleaner intake tube"

see that word rubber there, what if that leaks air.
the under hood HVAC parts there have vacuum tank to hold vacuum in reserve and it too can leak air .

I have cured vast vacuum leaks. on engines.
nature abhors a vacuum (on earth)
the end point sucks air. (like diaphragm devices and HVAC lots)
to see all vacuum things in my OEM SM
I had t type F3 100 times to find them all. find.F3 command.
PDF reader.
no single diagram is there in the book, , its on the VECI lable on car.
look under hood and up and under hood yet?


the PCM can go to limp home
and doing so can force the IAC to dead, OFF LINE,
so not scanning the PCM first is really bad idea. knowing just that.
good luck, !

Vacuum leak in the intake somewhere.

Random misfires could be gas related- low fuel pressure, vacuum leaks or air leaks upsetting the air/fuel mixture ratio, clogged air filter or fuel filter. Could be ignition related- worn spark plugs, possibly. Or could be an internal mechanical problem-possible valve train malfunction.
Start with a fuel pressure test. check vacuum hoses for leaks, check intake manifold and throttle body assembly for leaks. If you have an exhaust leak at or near the engine, can cause misfires. Air going into the engine is metered by the mass air flow sensor in the big air boot on the throttle body. If extra air gets into the engine through a vacuum leak or a loose hose, the engine computer won't know it, so the air/fuel mixture will be too lean, resulting in misfiring. Several things to check-good luck.

these engine have a problem with the pcv valve vacuum tubes splitting and causing a vacuum leak, will need for part number and go to dealer to buy replacement hose

do you have a small propane torch? or a can or throttle body cleaner or anything similar? Spray the propane(Just the gas, do nit light it) or throttle body clean, slowly around the engine and if there is a vacuum leak the rpm will rise when the propane fumes or throttle body spray gets sucked in and you know it will be in that area. Anywhere from the front of the motor to the sides to all the way behind, it might not be a vacuum hose, could be an intake manifold leak. Smelling fuel when shutting off can be a different problem all together.

There is no carburetor on any of the 6 cylinder or 8 cylinder Jeep Grand Cherokees. They have Fuel Injection and a throttle body which looks like a carburetor scaled down.

---
Instructions on how to remove and replace the throttle body follow:

Throttle Body REMOVAL & INSTALLATION

1. Disconnect the negative battery cable.
2. Remove the vacuum hoses from upper bonnet, unfasten the retaining clips and remove the upper bonnet assembly.
3. Remove the lower bonnet retaining bolts and lower bonnet.
4. Remove the throttle cable and the return spring.
5. Disengage the wire harness connector from the injector.
6. Disengage the wire harness connector from the WOT switch, ISA motor and TPS.
7. Disconnect the fuel supply and return lines from the throttle body.
8. Tag and disengage the vacuum hoses from the throttle body assembly.
9. Disengage the potentiometer wire connector.
10. Loosen throttle body retaining bolts and remove throttle body assembly from the intake manifold. To install:
    
11. Clean the intake manifold and throttle body mating surfaces of old gasket material.
12. Install a new gasket and the throttle body assembly. Tighten the mounting bolts to 16 ft. lbs. (21 Nm).
13. Engage the potentiometer wire connector.
14. Engage the vacuum hoses to the throttle body.
15. Engage the fuel lines to the throttle body.
16. Engage the WOT switch, ISA motor, TPS, and injector electrical connections.
17. Install the return spring and throttle cable.
18. Install the lower bonnet and fasten the retainers.
19. Install the upper bonnet assembly, retaining clips and vacuum hoses.
20. Connect the negative battery cable.
21. Start the vehicle and check for fuel leaks. Fig. 1: Exploded view of the throttle body and related components
    

common faults related to this are the top hoses on engine block and the inlet manifold gasket as the bolts are subject to corrosion from the water ways. Idle the car and spray detector spray around the inlet manifold to see if there is a change in engine note. also look to hoses from MAF unit to throttle body. Check all electrical plugs to the air/fuel system as bad connections can affect the performance of individual units. hope this helps - good luck.

have you checked for vacuum leaks? thought mine was spark plugs and found broken vacuum hose attatchment behind throttle body to manifold was broken... that was my problem, maybe yours too? It's the hose just behind throttle body on passenger side- mine was a broken rubber elbow right at top of manifold- it's reachable without taking throttle body off...

Definite signs of intermittent vacuum leak downstream of the maf. Check for leaks from the air cleaner to the throttle and all hoses on the intake manifold. Also check for leaky intake manifold gaskets.
Do It Yourself Diagnosis and Repair

Honestly i would say take it to the shop something like that should not cost you to much at all then you dont have to worry about anything.... But its most likely you Heater hose