Rough running - Need help and advice

[SharkPilot]

This may be a bit long-winded but I will be as brief as possible.
The car: 1991 #1135 with 23,000 miles. The only mods are a DRM chip and K&N filter with open lid.
I have owned it for three months and it has been running great.
The other day while idling at stop light it started to miss. Just a randon occasional miss. As soon as I started moving it went away. This happened at the next two stops. At the time the engine was cold.
On the way back from lunch and going home that evening it ran fine.
The next morning it had a rough idle and was very rough accelerating from a stop. The car runs great at cruise. In fifth gear at 65-70mph it's very smooth and gets 23mph instant mpg. It has low power and just sounded 'flat' when accelerating.
I had gotten fuel at a different station the night before it missed and suspected trouble there.
Next day I siphoned 10-12 gallons out and put 12 fresh in from my usual station. No change.
I replaced the plugs because I had been wanting to anyway.
No change.
Fuel pressure is 44psi at idle. Low according to the svc mnl but when I unplug the vacuum hose from the fuel pres. regulator, the pressure goes right to 55 and the idle does not change. Still rough with misfires.
Connected a scan tool and have no codes. All of the sensors seem to be returning normal readings. The long term block learn is 133 left and 134 right. Short term is 128 on both sides.
The oxygen sensors read very low at idle with spikes up to rich then back to lean. When the engine is revved up to ~2000 rpm the readings look more like the book says they should. Kind of like a sine wave rich to lean and back.
Yesterday at work we hooked up a smoke machine to check for vacuum leaks. When we pulled off the cannister purge line on the right side of the plenum charcoal particles came out. A lot of charcoal. That seems very bad to me as that stuff looks and feels pretty abrasive. How much has been sucked through the purge valve into the engine?? YIKES!!
We did find a vacuum leak at the PCV connection where that boot connects to the hard line. We put a clamp on there to get the car back home and that stopped the leak. A new boot will be ordered. We also plugged off the evap line. There were no other vacuum leaks that the smoke showed.
The idle was a tad better but still rough. The long term block learn was still 133 & 134. My co-worker, a GM master tech, said that on the way home it should start to run better as the ECM adapted and relearned now that the vacuum leak was gone. After an eight mile drive home in heavy traffic with a short run at 65 mph things are not much better. It's still rough at idle and has very low power on acceleration.
As of right now I am lost and not sure where to turn next. Does anyone have any advice or ideas?
Many thanks for reading through all of this and my apologies for the length but I wanted to be as thorough as possible.

SharkPilot