I know you said you have a new EGR but mine is 27 years old.

I cleaned my EGR 19 months ago, but I am pretty sure I did not push the pintle in, and clean out the carbon ridge with a scraper. I did push it in, and squirt carb cleaner multiple times. The pintle may not be fully seating randomly causing an EGR slightly open at idle.

I am thinking if I crank the engine, and let it idle. Spray a squirt of carb cleaner in one of the vent holes on the EGR. If the idle changes, then the EGR is leaking closed.

 

Yes, EGR & modulator are new and OEM but didn't solve the problem. I did just install the LCE TB rebuild kit (no idea why they don't include a new shaft & plate screws instead of a fancy idle screw?) but haven't taken the truck for a ride yet. I also made sure that shaft was well oiled where it makes contact with the seals and TB. Will update once I take the truck out.

Let me know what happens with the EGR test, if it fails I will gladly send you the one I took out. "Only" has 120K miles on it and appears to be in pretty good shape.

 

LCE TB "rebuild" kit & oiling shaft did not solve the problem. Still idles at about 500rpm when starting truck after it is hot and have to blip the gas to get it higher. However my idle now won't go below 1000rpm, even with idle screw all the way in. Not sure what next step is besides replacing the TB and TPS? It does seem to hunt for an idle and never rests in the same place. What circuit controls the idle up when the truck is cold? Is there a chance my problem is electrical? I will check the AFM is within specs with a meter today. One thing I did notice when changing the TB seals is that I do have a slight gap on both sides of the TB plate, seems this may be the culprit for the high idle and hunting. But why the low idle at hot startup?

 

If there is no/not enough coolant in the idle air valve, it won't idle right.

 

Idle hunting actually worse since I put in the LCE kit, but maybe I screwed up the shaft trying to get the 2 plate screws off? Dashpot and IACV are new. I am waiting for another used TB and will see if that performs any better after I clean it up real good and put in new seals. This is my temporary fix with a spring I had laying around to get the RPMS below 1000 until I try out another TB. What I noticed about the low RPM after hot startup is that problem is worse if engine sits for a bit but still hot enough that the idle up circuit is not in play. If I start the truck back up immediately after shutting it off, it idles fine. What I am thinking is that over time I lose some fuel pressure, and the heat soak with fuel vapors in the rail lead to the low/rough idle.