Engine stalling

190,000 MILES • 5.7L • V8 • 4WD • AUTOMATIC
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TEALWOOD
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  • 2 POSTS
Starts great, runs fine on high idle cold engine. As engine begins to reach operating temperature, idle speed will reduce marginally. Shortly thereafter engine will dramatically slow down and stall. Occasionally, engine will "recover" itself and return to normal idle but will quickly repeat slowdown and stall. At operating temperatures engine will stall as soon as it is shifted into any gear. Can keep it running (stationary) at operating temperature by keeping foot on gas pedal so it rums at higher speed. Can sometimes force it to "drive" (a very short distance, length of driveway) using two foot method but engine hesitates and sometimes backfires and then stalls.
Oct 30, 2017 at 7:35 AM
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KHLOW2008
  • ✓Experienced Mechanic
  • 41,812 POSTS
Looks like the engine idling speed is too low.
Is the check engine light indicating?
I would suggest having the throttle body cleaned for a start.
Check for vacuum leakages along air intake hoses.
Oct 30, 2017 at 3:48 PM
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TEALWOOD
  • MEMBER
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Check engine light is not on. Throttle body has been thoroughly cleaned .... no change. Could not find any vacuum leaks. Disconnected iac and engine stayed running smoothly even at operating temperature, but at high rpm approximately 1400. However, if shifted into gear it immediately stalled.
Nov 5, 2017 at 2:13 AM
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KHLOW2008
  • ✓Experienced Mechanic
  • 41,812 POSTS
Did you clean the IAC as well? The IAC is not responding to stabilize the idling speed when load is turned on as you engage gear.

If the engine runs smoothly when gears are not engaged, the problem could be due to a fault with the torque converter. Did you check for trouble codes? Some transmission trouble codes do not trigger the MIL.
Nov 5, 2017 at 1:31 PM
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