So i clicked over 133K miles this week and now i have random idle surge. truck internally is stock... has a headers, intake, exhaust... which have been on for a few years..

The rpm will be a 800 then drop down to 400-500 for a few seconds then jump to 1000.. the air fuel gauge goes from 15.4 to 16.8 then shoot to 13.2 ish... then back to 15.8 or so.. and idel is back to normal 800... then a minute or so later it does it again.. But no always.. some days its fine runs all day with out doing it..

So would that be like a dirty fuel filter or what?

 

Mine does the exact same thing some times.. Could be a vacuum leak of some sort, but I am going to listen in on this post.. I have yet to find my problem, or a vac leak....

 

You get something liek this kinda??? I corrected some of it, but my AFR just hangs on the fat side for a long time some times..

 

Clean your throttle body. It only takes a tiny bit of build up to start doing that. Especially if its the DBW

 

As in the blade or what. My TB was spotless last time I checked it, I do not run the pcv system back into it..

 

Yeah in your case, that might not be the problem. But it doesn't hurt to check anyway. Oh and yeah, clean all around the blade and body. I've seen the smallest amount of build up do alot!

 

I suggest that you clean the idle air control and passages.

 

For him and me both, I will check the IAC tom, see if it is shitted up. I have never check that at all, just the TB blade and bore....

 

Clean throttlebody.
Mangled,if your afr goes rich when the idle falls,you may need some injector data adjusted,just a thought.Going rich can also cause the surge or make it worse but not always

 

Cleaned the TB today. It was not all that dirty... Next is where in thee *** is the IAC.. I looked, didn't see a thing in or on the TB other then the blade.