This is what i know so far, not that these may cause this issue, but im new to vehicles in general:

Visible exhaust leaks from the headers and manifold

I have cleaned the IAC, MAF and throttle body
Also has a k&n air filter and have took out auto locking hubs for manual

I cannot figure out what would cause an idle "surge" that almost sounds like a lope, but in a gasser. here's a video:

https://www.youtube.com/watch?v=u3chsaL3jGk

 

Based on the sound, one possibility is a stuck EGR valve (I believe I saw one on the the video). This does tend to get over diagnosed, but my 5.4L had a similar surge recently and the EGR valve was stuck open.

How is it when you are driving?

 

It depends on if i let it fully warm up or not, if i just start and let it semi-warm up it drives fine unless it's idling down when comming to a stop, it will surge. But if i let it warm up, it takes 30 seconds of driving of it surging while accelerating aswell about the same pace as you heard my exhaust

 

The other two times I had surging at Idle with hesitation upon acceleration it was: (1) The vacuum line to the fuel pressure regulator was chewed through by a rabbit. (2) A crack in the elbow that connects the hose from the air intake to the back of the intake manifold.

 

Okay so checklist, EGR, vacuum line to the fuel pressure regulator.
I have felt around the elbow for any crack with air coming out and i havent felt/seen anyt on that.
If my egr is stuck, how do i go about checking that? and do i need a new one or can it be cleaned.
And do you have a picture to show me where the vacuum line to the FPR is?

 

Is your check engine light on? Any codes?

I would check all the vacuum lines for cracks and proper connection not just the two I mentioned before.

If the egr valve is stuck open you can some time tap it and it will close. One way of testing it is to connect a hand vacuum pump to it in place of the vacuum line and slowly apply a vacuum (with the engine at idle). A plastic syringe (35 ml) and a small piece of tubing can be used in place of the vacuum pump. If the valve was closed initially and and opens under vacuum the idle should change. The engine will noticeably stumble. If you get no change, then either the valve is faulty or there is a blockage in the egr tube.

You can clean both the egr valve with carborator/throttle body cleaner. Sometimes this restores function.

Your DPFE could also be faulty or the line leading to it could be plugged.

Another possibility is if you have a visible exhaust leak this could be allowing air in to the exhaust causing the oxygen sensors to give incorrect readings.

There are several possibilities so it would be helpful to no if it has thrown any codes or if there are any pending.

 

From the 3 times i've checked for codes, it only threw a IACV code, so i cleaned that out and put it back on, and checked twice more with no codes at all.
The visible leak is where the headers meet the manifold, there are a few more but those are past the o2 sensors and shouldnt be a bother right?

Ill try tapping on the egr, along with hand pumping it at idle tomorrow. But i won't be able to check vacuum lines for some time since it drops to -25 here and i have no access to a heated garage

 

The thick line that bends off to the right goes to the brake booster.
The fitting below that hose is the FPR vacuum line connnection.
I hope this helps.
http://i1164.photobucket.com/albums/...psb94bfc5c.jpg

 

I believe you said that you recently switched to manual hubs?

Did you properly cap the vacuum lines that supply them? Both EGR and vacuum leaks can cause this. Any stalling issues? You can use a can of starting fluid (be extremely careful!!!) to find the leaks. Unfortunately most auto store code readers won't check the function or the specs at which a switch or solenoid or sensor is operating at. Also make sure your ac is off. When the ac kicks on it'll make the rpm change. The best thing to do is to unplug the clutch so you know for certain isn't kicking in.

On a side note. I'd pull the nipples on the hubs for the vacuum supply and install 1/8 npt plugs there instead. I recently rebuilt my front in and the po had done the switch already. Unfortunately the rubber vacuum caps he installed on the hub nipples rotted and allowed moisture into the hub. Not his mistake, just those black rubber plugs tend to do that. I use the silicone ones instead now.

 

I would lean towards egr or vacuum leak or the IAC is faulty. Cleaning it doesn't always work. Definitely check that the vacuum lines to the hubs were capped off when you switched to manual hubs as SasquatchZilla.

I assume the IAC code was P0505 (possibly p1507 or p1505). In addition to dirty or damaged IAC valve assembly, this code can be thrown as a result of:
Air intake leaks or restrictions
Vacuum leaks
Loose or damaged throttle body
Faulty EGR valve or gasket
Faulty PCV valve or hose
Faulty Powertrain Control Module

 

Feeling is not good enough. Try using CARB cleaner and spray around suspected area of intake manifold.

Plus...IMHO...the IAC really should be replaced...and not cleaned. Just my experience...


biz

 

@Zedrive Thank you for the picture, i'll be looking at it tomorrow!

@Sasquatchzilla I'm not 100% sure, i'm a 3rd owner, and the 2nd owner was the one to switch over to manual hubs. For stalling issues, yes, it would stall when going into reverse 90% of the time, but to avoid this i turned the idle up for now. And it's weird, from what i see, the AC is plugged in, backwards? i'll have a picture tomorrow as it is dark if you need it. And for the nipples, i think there is just a cap on them, does that sound like something that would work?

@tawells01 The code was P1504 (Idle Air Control Circuit Malfunction) does that change anything?

@biz4two Thanks! Yes, i know it was just a quick feel around for major cracks, and i'll have a IAC ordered tomorrow

 

This DTC is set when electrical load failure on the IAC output circuit is detected.

IAC circuit open
VPWR to IAC solenoid open
IAC circuit short to PWR
IAC circuit short to GND
Damaged IAC valve
Damaged PCM

 

By the sounds of it, i may have a few connected problems to make it idle this way, if it was electrical on the IAC, don't you think it would be always pulling P1504? i only got it to happen once, and when it happened, i was cruising 110 KMH and floored it and it popped up to 4000 RPM or so and the CEL came on and that was the code i got

But im going to be ordering a new IAC today regardless, relatively cheap at 70$