2001Jeep Grand Cherokee 4.0l Idle at start up

Possible trapped air pocket. Set to full heat position, lowest fan speed, remove rad. cap, start engine and let idle for 10 minutes, then hold gas pedal at 1500rpm for two minutes then let idle for two minutes. Shut engine off , let cool for 30 minutes. Top up coolant level and reinstall cap. Drive vehicle, should get heat now.

thats a lean code have fuel pressure tested

it is your air idle control valve witch is located on the back of the throttle body..

Because you disconnected the battery you lost the long trim value,you will now have to relearn the idle,start the vehicle idle it to 1500 RPM,hold for a minute,idle should stabilize,turn on A/C let it idle,for a minute,now your done,

if you can keep it running by pressing on the gas pedal then clean the idle air control valve, IAC.
If, however, it runs for 2 seconds then shuts off and no amount of pressing the gas pedal helps then check your crank position sensor.

All you need to do is hold your foot on the gas pedal to start and hold to keep engine running, hold gas pedal for about 3 minutes then let idle, computer needs to relearn the idle speed thats why it stalls out, hope this helps,

You do have a filter and it's mounted right on top of the pump on outside of tank...it is also the pressure regulator. You really should put a pressure gauge on the fuel system and check it out though. you may find there is a problem elsewhere. Good and proper testing is the only way to get answers about problems especially now that systems are all electronically controlled.

the computer probably need to relearn the idle-try driving the car for 20-30 minutes,i u can. if that doesnt work,try keeping the car in drive at idle speed if possible without touching the gas pedal-even though it might stall,see if eventually the idle will raise up on its own.hope this helps you.

Check and clean Idle air control valve. Make sure its responding to signal as well. Also make sure ther are no vacuum hoses disconnected. This may not be a "cure" but it's a good place to start.

The problem could very well be your Idle Air Control Valve. If you're a handy person it costs about $40.00 and takes 10 minutes to replace. Best way to check it is to unplug it while it is running. If the valve is bad it will keep running. If it is good, unplugging it will shut the engine off, and that means it's doing its job. Happened w/ my dakota and I'm about to replace it in my Grand Cherokee.