Hello again,
Maybe someone has experienced the same issue lately. My 2002 F-250 sat for about 2 months while I began different repairs on it. It's a 2002 f-250 5.4L 4WD XLT with 225,000 miles. Today was the first day driving it and it was a 30 mile round tripper. No issues whatsoever. Ran great, filled with gas and no issues with idling. Back home in town here and there, no issues and definitely no stalling. Came back from work, pulled into driveway and stalled. RPM ran to about 500-600 then quit. Restarted it and had this flutter where the RPM gets to a 1000-1500, take foot off gas, RPMs go lower and moderates and then stalls. I was in a drive thru lane last night, with foot on the brake and in "Drive", idle was about 600. No problem. Shifted to "Neutral" and then Idle fell and then stalled. It does not sputter when driving, only when low idle is experienced. I dumped some Lucas Injector cleaner into the gas tank. Tomorrow, I'll get a look into the throttle body, spray some Throttle body cleaner on a rag and wipe inside and try to get it cleaned well. Last complete tune was 4 years ago. Could it be that it sat for 2 months. During that time I did run it a few times. If anyone can suggest something, I'm all ears.

 

When was the last time you checked the transmission fluid level when hot? What you are describing is typical low level symptoms.

Is your OD light blinking? Have your used FORScan and pulled codes?

 

IDLE UPDATE!!! I took the advice of a friend and used Berryman B-12 ChemTool and sprayed it on a rag and went to town inside the Throttle body. Yes, there was plenty of carbon in there. Cleaned it out as best I could and cleaned the door too, front and back. Upon start up, it sounded as good as it ever has. RPM crested over 1000 on the start up and settled at about 750 which is the sweet spot for this truck. There is no flutter or hesitation in the idle at all. I let it run for about 10 min then took it for a test drive. Super-better!!! I didn't have to work the gas and brake pedals simultaneously as was the case yesterday, to prevent it from stalling.
As far as I could reach in to clean the Throttle body, what can be done to give it a GOOD cleaning? For the springs that control the door, can they be sprayed/lubricated or not? Is it worth it? This throttle body is original at 20 years and now a fella is thinking how can I clean it to get better performance.....
Any thoughts??