Slight jerking/noise at steady speed

A few days ago as I was driving around I noticed a popping noise (like popcorn) that would occur. It wouldn't happen very often and there was no effect on performance so I shrugged it off. As I was driving on the hoghway however, the noise became more frequent with tiny little jerks occuring at random points. It wasn't shaking like a misfire and there were no drops in RPM at all. No performance lost. If I gave it gas, it wouldn't do it. The only other time it does it is when I go up a hill gradually increasing my speed. I ran gumout fuel injector cleaner through it, and it seemed to temporarily help but its doing it again. No codes appearing either.

Intake plenum leaking?

Trust me, I dealt with a leaky plenum for years before I finally got a real job so I could get it fixed. Spark knock, plug fouling, random misfires, oil smoke when warm-starting (that was particularly embarrassing), the inability to use overdrive because the truck would shake like all hell when I tried to use it. Oh and combined with the death flash, I literally had to push the truck just to cruise 70 (I couldn't even hold 65 near the end).

What I'm saying is the plenum leak will cause a TON of problems and only gets worse until it's fixed.

Now, if you or someone else has fixed your plenum, then we can forget all that.

Also, as an aside, I had to stop and laugh when I read "hoghway." For a second, I honestly thought that you were intentionally referring to the highway as "hoghway" in reference to regular bad drivers on it.

It's got about 132k and drinks oil like water so I bet it's the plenum. I've had an incident last winter where it was misfiring horribly due to fouled plugs.

I would definitely recommend starting there. Once that's done, you're still probably going to have a ton of carbon buildup on the combustion chambers and pistons which may act as hot spots and may still result in knocking. As far as dealing with that goes, I really couldn't say. Inducing Seafoam into the engine while it's running is said to do a good job cleaning the interior of an engine.

In my case, I ended up just replacing the heads since I had the money at the time to do it and upon examination, the old ones were cracked in multiple spots. And yes, the chambers of the old ones were VERY dirty and it looked like a couple of exhaust valves were getting pretty toasty.

All depends on how far you want to go and how much you wanna spend. At the very least, fixing the plenum will resolve your oil consumption, fuel/air contamination and plug fouling. It should also help your fuel economy but I personally noticed no measurable difference in mine.

Look at cyl 8 plug and next tank of gas put 91 or 93 instead of a regular 87 or 89. Likely pinging and that'll confirm it if it goes away or is drastically reduced

^ Good point. 91 reduced my knocking a fair bit back then so I ran it as much as I could.

Going uphill at 25mph would cause the popping sound and sometimes the exhaust noise would cut out for a split second

That honestly sounds pretty extreme for a plenum leak. You might want to consider renting/buying a compression tester and checking things out. I noticed that you have an MSD coil. Did you have to buy one of those adapter thingys to make it work?

Have you scanned the computer for codes? Even if you don't have a light, the computer may have a "pending" code or two which could be a clue to your woes. "Pending" codes will only trigger the CEL if the computer can't resolve the issue on it's own but that certainly doesn't mean that you won't have driveability problems in certain situations anyway.

Not really. It's when he puts it under load. That's when issues like this will be most apparent

MSD Coil didn't need an adapter, but its been on there since January. I've checked the codes and the only ones on there tell me my O2 sensors are missing, which I already knew. On my drive home I noticed it wasn't doing it on the highway at 55, but after I ascended a hill and started heading down, I slowly released my foot off the accelerator and it would sputter/pop and jerk a bit as described before.

You're still running with no O2 sensors? Not even the upstream one?

LOL, put those buggers back on. The upstream one in particular is going to cause lots of driveability problems as the computer relies heavily on that one for fuel management.