Next: new ignition control module (ICM) & ignition coil (IC), PVC valve + hose, oil + filter.
(Ok, ok, we are up to about July/August 2020 now...)
After the previous rounds of maintenance, I was still having a hot stall issue. It would usually only happen after a longer drive (over an hour), but it was consistent. I was also getting a stumble while idling in gear and the tach was randomly bouncing. Not physically raising the RPM, but the tach gauge would bounce, while sitting at a red light for example.
Back in post #41, I had this problem "fixed" by a shop a few years back. Well, upon closer inspection myself (and a few years of self taught mechanics under my belt later), they had replaced the ICM with a P.O.S generic parts store brand. I had read dozens of posts (mostly on here) about the bad track record for our trucks vs. generic ICMs.
The IC terminal post was also damaged, seemed suspect. I tested the plug wires, they all ohm'ed out to spec ok. Check all grounds etc. Basically did a once over on the Ignition system, cleaned and gapped the spark plugs.
So... a new AC Delco ICM & IC went in. Pretty straightforward job, used a good dollop of dielectric grease under the ICM. I also cleaned all grounds to bare metal, added a new big braided ground strap from block to frame, and replaced block to firewall ground with 2 ga wire, the OEM one was totally broken into two. I love the crazy s.h.1.t we find on these old trucks.
While I was at it, I did a few other some things. Ran seafoam top engine cleaner through the intake at 2000 RPM. Took the truck for a good rip, lots of heavy throttle, then let it heat soak for 15 mins before draining the oil. Installed new oil & filter, and a new PCV valve.
For good measure, I ran the truck at idle for awhile while I checked for vaacum leaks. The poor quality Dorman PCV hose I had previously replaced leaked. I dont recommend this product BTW, very crap. I threw it in the trash and cut a length of left over oil cooler line I had lying around. It fit snug and I had no more leaks. Better than it was.
I also listened for the stumble, all gone. The truck has been running smooth since! Good times.
(Ill go look for some pics for you all...)