I just bought a 2006 f150 regular cab short bed with 100k miles 4.2 v6. The only issue i have is when i start it it cranks and turns on but starts to act like it wants to die ans gets to 500-600 rpm then jumps back up to 1200-1500 rpm. Every time. In Park it will also feel shacky but in Revese or Drive its ok. I pulled codes and p0442 came up but i bought a new gas cap and the idle did improve a little but not the starting issue. The code hasnt come back after i changed the gas cap. Could it be the IAC? The plugs look new but i dont know if the coil was done. I can only assume he did the spark plugs and wires. Hoses look good around the engine aswell.

 

There is no IAC, you have an electronic throttle. The throttle body probably needs cleaning. Remove it to do it, take care that you don't work the throttle plate open and closed while it's disconnected.

 

New to the site and 2006 F150 s,

i have the same issue, my bud hooked it his code reader and told me IAC! i ordered one for my 4.6 V8 and they found me the part. to my surprise i couldn't find the IAC on my truck. youtube videos Shows 06 having one. Rockauto shows a listing now i read this post and you confirm that my truck does not have an IAC. I must admit this is confusing. wish i have looked here first, hope they take it back.

thanks Guys

 

If you are getting an IAC code on a 2006, you have a throttle body issue. Cleaning it may fix it, if not, a new/rebuilt one is NOT cheap. It *might* be the throttle position sensor, but not terribly likely.