Ok, first issue was starting, idling for 5 minutes and then stall. Had codes for air and ECT. ECT checked out, air intakes checked out, did find the small bend hose from the flame trap to the engine was split open (how I didn't notice it I don't know). All those fixed.

Engine starts, idles for over 10 minutes (yea for me) and shut it off. Check codes, got one for 2-3-1 and one for 1-4-3 knock sensor.

Knock sensor, I forgot to disconnect, fixed.

2-3-1 says Fuel Trim (lambda control) too lean or too rich at part load.

Reset codes. Starts this time but only idles for 90 sec. Hmmm I say, but the knock sensor was disconnected and it ran for 10 min. I disconnect knock sensor and same result., 90 sec idle before stalling. Knock sensor hooked back up.

Cleared all codes, same 90 seconds to stall symptom.

#6 port is clean, no codes.

#2 port still showing 2-3-1 code.

For kicks I took a look at the O2 sensor. Got engine up to temp, shut off, tested the resistance at the double wire (3 wire sensor), only getting 5-6 ohms (Haynes says should be 13 when hot, 3 when cold. Could be the culprit?