Rod Knock
 

*QUICK UPDATE* The situation is both bad, and not so bad, at the same time.

The BAD: There IS a Rod Knock. Initially thought it was coming from the top.. now seems to be coming from the middle/bottom more. (Had car up on ramps today. Put in 20W-50 motor oil. Some improvement. Knock still there.
Car still stalls when at a light and brake pedal depressed/surges. Brake booster is leaking badly, LOUD hissing sound from brakes.

The GOOD:
- I still have oil pressure (ALL of it.)
- The car drives perfectly.

WHAT I THINK HAPPENED: Aggressive induction cleaning (SeaFoam.. just with MMO. I have to say, I've done this before.. cracked a coil or two on a GMC with a Vortec 4200. Resume) led to situation to "spin a bearing;" Somehow, had one instance of the engine "racing up" to bounce off rev limiter and this knock started shortly thereafter.
Possible one cylinder "contributing poorly" .. Maybe it sucked an electrode out of a spark plug? (That happened on a previous blazer and it did pretty much exactly what mine is doing now, including occasional stall.)

What is the next thing to do?

And what are the chances the "Pull off the oil pan and change a bearing or bearings" trick will do it? Seems like its showing "5 out of 6" cylinder behavior at idle, with the gear selector in drive; it idles just fine in park with the brake pedal not depressed.

If you ate a bearing you could have damage throughout the engine. However, it could be worth a shot.

You have another thread on this going. Don't post same thing both places.