My truck has been having an issue with the idle since I bought it and it is driving me crazy. When it gets up to operating temp and I come to a stop, it idles at 600 - 650 for the first 10 seconds I am stopped, after that it drops suddenly to 500 or lower and acts like it wants to stall out. It also does the same thing sometimes when I put it in park, drops suddenly then comes back up to normal idle speed.
I searched the site and found someone had a similar issue when they put their truck in park and said it was the crank sensor. I have replaced the battery, plugs, fuel pump, and cleaned the throttle body, all to no avail.I have located the crank sensor and camshaft position sensor and would be willing to change both out myself if I thought they would help. Would somebody please give me their opinion if these would help at all with the idle issue, or what else would you suggest. I absolutely love my truck with the exception of this issue. TIA.

'01
4.7 QC

 

Have you checked the throttle position sensor ?

 

did you clean out the iac(i think thats it im having a brain fart). it is a plunger type thing and when i took mine out it was completly gunked up...really helped it idle more normally. you might have cleaned it though when you did the tb. i second the tps^^suggestion. mine was bad when i got mine and they replaced it and it helped her idle better as well.

 

i had the same problem with my 3.9. It was the IAC. very quick to install. When you first install it you may have to reset it. In order to reset it you have to drive at 40 mph for a little while. maybe about 5 minutes. When i put mine in it idled high, after reset its been fine ever since