On the later OBD 2 cars this is called throttle follower, it mimics the old dash pots on carbureted vehicle. You can adjust it for more or less delay

Keep Alive, Memory Power, B+ all mean it is fused battery positive.

Hot in run/crank is the ignition/injector power that is only hot with key in crank or run position. Not ACC or OFF.

See...

"ECM 1" is only hot in start/crank. Make sense?

Relay can this be an ordinary relay with a suppression resistor built in, a normal ice cube relay that has is 5 terminal is all you need. The wiring diagram is correct, but confusing.
...

EAC=Electronic Air Control - it controls the solenoid that controls the air pump flow, it can be safely eliminated for your application, I am assuming you have eliminated the air pump.

You can...

You are correct in saying that you should not have to train the IAC valve. There are baseline settings that should work out well, but you're dealing with a 35 year old vehicle with unknown repair...

Your base fuel settings are "128"on fuel trims. Once the computer is cleared it resorts to the 128 setting, and then modifies it with the oxygen sensor for your BLM setting (below 128 the computer is...

There are multiple people here to help. I would monitor your fuel pressure, timing, and fuel trims. It might be just the PCM. Let's see what the data log shows.

Don't give up the fight. We're all pulling for you.

I have no experience with DRAC modules, but a quick Google search turned up:

https://www.udmodule.com/

https://atracom.blob.core.windows.net › gears › 2005 › 2005-04 › 2005_04_04.pdf
...

Stray voltage can happen when you have high resistance at ground connections. Instead of going to ground to complete the circuit, it backfeeds into other circuits causing havoc.

That would be a new one on me, it shouldn't have anything to do with the idle speed fluctuation, but circuit grounds cause all kinds of weird symptoms when voltage gets back through the circuits,...

I know you said that you checked powers and grounds, but how did you do that. With an ohmmeter, or the voltage drop method? An ohmmeter will just tell you whether there is continuity, voltage drop...

Go to beginning of your post, start there.

I would add to the list of things to inspect, the inside of the distributor cap. Remove the cap and blow out the distributor with air, then wash the cap and rotor with warm soapy water. The coolant...

I have a stroked 05 LQ9 DBW in my 99 Yukon I running a service number 12589462 P59 PCM running the 7603 operating system. I have the engine running great and the only problem is I'm having with the...

Those that never make a mistake are never doing anything. We've all been there, done that. The best lessons for me are the most painful, makes it kind of hard to forget. I worked with a guy once that...

Typically the increase in fuel pressure, related to intake vacuum, is only 4 to 10 psi. I have thought for years that that was to compensate for the difference in intake manifold vacuum versus fuel...

I do not know the definitive answer to your question, but my my reasoning if either parameter is met it transitions. That means at 45 miles an hour, decelerating, with your foot off the throttle, it...

First of all, since your troubles began when you were welding on your truck, it is very possible that you damaged something inside the PCM. Did you disconnect the battery prior to welding? The wire...

Ignition timing, improper firing order, to lean of fuel mixture, are some of the other issues that will cause backfiring through the intake.

If you have access to a lab scope, you could "see" the output of the pickup coil

Glad things worked out for you, and you figured your son-in-law's truck out also. It helps to get these dialed in to understand carburetors and what the various settings are that affect drivability,...

Yes the reluctor can go bad, it gets magnetized and throws things into a tizzy. Since you have a two-part housing could be spark be cross firing between two different spark plug terminals, i.e. is...

The remote reservoir works well, the only problem with it on jeeps is space. You are kind of limited in where it will fit. Edelbrock, Holly, and FiTech all make their own remote reservoir systems.