My 99 F150 4.6L with Manual transmission has had an idle problem since about 8000 miles,it now has 24000. I will be stopped at a traffic light , for example, it will be idling norrmally and then without any apparent reason the idle speed will drop and then immediately recover. I have had it at the dealer 2 times for this so far and they can't find anything wrong. This is especially dangerous when turning into a parking place, etc., and you lose power, then you momentarily lose power steering and power brakes. It doesn't matter whether the AC is on or not and it was doing this before I had dual exhaust installed. Also I have only noticed the stalling after the engine warms up
Any ideas??

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LTDC
99 F-150, ext cab, 4.6L, 3.55 gears, limited slip, manual trans. catbac exhaust

 

Check out the topic titled "FYI: 5.4L F-150 Owners..." , also in the Engines forum.