2002 S80 T6 misfires when cold

[EChem]

Dear All:

New problem. Replaced plugs about 6-8 weeks ago. Snapped the overflow coolant bleeder hose nipple on reservoir tank and at thermostat housing. Got those replaced. Had also crimped ECT wire so temperature gauge not working, and drove for 2 weeks (ca. 300 miles). No problems there except after 1 week, wife mades short trip with 5 stops shopping and at last stop car wouldn't start, then started, ran very rough and she got a bad gas smell. She got it home. Next morning before work, I was going to clear computer figuring the lack of temperature feedback to computer made it rich out fuel mixture, and when I started it to check before going to reset, started and ran fine so just drove it short distances for the next week. Replaced the ECT last Sunday. Didn't notice it Sunday night when I ran it to get thermostat opened up so as to bleed the air from the coolant lines and took for short test drive, and seemed ok. The next day car on 1st start it would stall. Revs start at about 1500rpm, after 10 seconds, drops to 800-1000rpm, and after another 30 seconds or so drops to 400rpm for a few seconds (stall), comes back to 800-1000rpm. Will drop to the 400rpm every minute orso when idling or starting to drive. Don't notice after car warmed up and driving. Don't have VIDA/DICE or another OBDII scanner (been researching to get one but that's another thread). Check engine light on (also have had the SRS- Airbag service urgent on DIM for awhile), so disconnected battery and hooked terminals together for a half hour or so hoping to reset computer from the ECT/temp gauge not sending temp. to computer (is that best way to reset that?). Check engine light was off, but came back on and I know codes usually stored until cleared with a scanner/DICE.

Stopped at AutoZone yesterday to get codes read. Scanner read no codes after 3 tries, rep. said they had switched to a "cheap" scanner. Stopped at O'Reillys and got P0300 "Random Multiple Misfire", P0305 "Cylinder 5 Misfire", P0306, "Cylinder 6 Misfire", and P0303 "Cylinder 3 Misfire" codes. I don't believe in coincidences so I feel this is related to some of my repairs/problems. Some vacuum hose leaking, more thorough reset of computer, etc?
Any help is appreciated! Thanks.

EChem