Truck unexpectedly shuts off

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Tom R

Active Member
Joined
Jul 20, 2003
Messages
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Location
Goose Creek, SC
Ok, I'm at a loss here. Some guidance would be appreciated. My '03 XLT Premium with 174,000 miles has really started acting up in the last week. About a month ago, I noticed after starting it would idle at about 2000-2500rpm. Sometimes it would do it, sometimes not.

As of last week something else is going on I can't sort out. Tuesday sitting at a stoplight, the truck just dies, it restarts ok and nothing else happens. Yesterday, I'm driving home from work in rush hour on the interstate doing about 50-60 and out of nowhere the truck just shuts off. Turned the key to see if it would restart, got nothing, threw it in neutral, turned the key all the way off and back to start and the truck starts up. Kept on my way to try to get home, dies twice more in 8 miles.

Got up early this morning to look for an obvious problem under the hood, see nothing out of the ordinary. Start the truck, it idles just fine at about 1000rpm for 15 minutes, I did find the transmission about a half quart low.Topped it off and monitored the truck for the next 15 minutes before heading off to work. Had no issues on the way there.
Left work going home with the idle acting normal and the truck dies about 7 or 8 times in stop and go traffic and at a couple of stoplights. Noticed a couple of times, the engine rpms dropped real low and then lurched back up before settling down.

I'm leaning towards the IAC, but the engine light and theft light flashed like the truck was off and the key was turned to start the engine or power was cycled and that's the part that scares me. IAC and MAF are easy to clean, intermittent electrical issues are a real PITA!
Tomorrow I'm gonna pull the IAC Valve even though it was replaced last year. Gonna check the Throttle body and MAF as well. Any other Thoughts, Ideas, Things to Check? Thanks!
 
As a thought. I would check the connectors on all sensors. Maybe unplug and replug. Could be corrosion, causing high resistance. Or intermitent issues. Afterward I would pull the neg batt cable for 10 minutes. Start it and let it idle to relearn idle. Drive and see what happens.
Maybe check fuel pressure also.
 
Scan for trouble codes too. Unless cleared or the battery was disconnected, a check engine light is NOT needed to have stored codes in memory.
 
Check for vacuum leaks... Check the common elbow, other hoses and basics.... it could also be the fuel pump....
 
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