2007 XLT 4.0 Idle Weirdness

[grfo]

Hope everyone had a great thanksgiving!
2 issues -
First of all, the car fires immediately, but, generally has an erratic idle initially.
Once warm, when I try to start it, it will fire and then idle roughly and die. If I rev it a bit and get it into gear it will get going and be fine thereafter.
I'm thinking IAC?

2nd issue - I haven't driven it in a week. Changed the tranny filter & fluid before I left town for the holidays, all was fine. Today - coming out of park it revved up and then dropped abruptly into gear. I checked the level of the tranny fluid after I changed it, actually overfilled it by several ounces which ran out after the road test. I used a level on the running boards to get the vehicle "level" before checking. It's not leaking that I can tell. Who was the moron that that a dipstick was optional?!?

Thanks for the help!

 

[grfo]

Idle is much improved.
I think the issue after I did the initial transmission fluid change where the RPMs raced up before dropping into gear was because the level in the tranny was not correct. I did a second drain and refill of the transmission and that issue has not occurred again.

With respect to the erratic idle, I did the following: on consecutive tanks of gas I ran a bottle of Chevron techron fuel injector cleaner, Replaced the spark plugs and I cleaned the MAF sensor per the note posted with electronic parts cleaner. While I had The MAF sensor drying for 20 minutes I had the ground to the battery removed.

It has run remarkably better. The biggest difference was after I cleaned the MAF sensor. I used the factory replacement Motorcraft plugs, did not do anything fancy with those,..

I also ordered a new PCV because I'm sure it has not been replaced. I am also going to go ahead and change the spark plug wires out as well. I'm sure they have not been changed either.

 

[grfo]

PCV is a bear on these things. I gave it a half hearted effort and gave up temporarily. Installed new plug wires, easy job if you remove alternator (3 bolts, not major surgery).
Wires made a definite improvement.

When cold, starts readily, idles smooth, drives great in all conditions - around town or on highway.

When it's warmed up and I make a short stop for 10min or so, it readily starts, but, the idle is rough/ erratic.

Up until yesterday it no codes. 300mile Road trip Yesterday. After first stop for quick bfast I got misfire codes on cyl 2 & 3. Drove fine at once we got going. Cleared the codes drove another 100 miles no codes.

Any ideas??

 

[grfo]

Replaced the fuel filter and the PCV valve. The idle has settled down considerably - something I did not mention previously is that the throttle response was very sensitive . That has cleared up entirely. I believe it was due to clogged fuel filter.

I have seen other threads as well where people replaced the fuel filter and remarked that the idle performance was improved as well.

 

[07EddyB]

Sounds like you are getting things straightened out. I apologize for not jumping in but I have an 8 and don't know much about the sixes. Thank you for documenting your work even though you didn't get any help - it really helps build a helpful database for everyone. If everyone did what you did we would have a treasure trove of information here.
Kudos

 

[Beachcomber86]

Have you checked your wiring harness for bare wires? Common areas are the MAF, fan connector, distributor, and TPS.

Found my ghosts in the machine