Hello all. I'm fairly new to the Brickboard so feel free to boom me if this has been anwered before:

'00 S70 AWD, 121k, US market, 4Spd Auto Trans. Recent work: New evaporator, new camshaft valve (emissions), New coolant expansion tank (old one was leaking). 105k service was performed 1 year ago.

Driving the other day and the car suddenly started running roughly. Check Engine light (steady, no flashing) came on shortly thereafter. Drivablilty extremely poor. Idle slightly rough, but doesn't stall. Runs more smoothly at cruise speed/constant throttle above 40mph, but has a hell of a time getting there. Exhaust odor is altered, bit of unburned fuel vapor, I think.

Took the car to AutoZone for a code read on the OBDII and it had a single P0305 (misfire on cylinder 5, if I understand correctly) code. I immediately suspected the #5 coil. Procured new coil, installed. Checked the associated plug and found normal-looking deposits, no damage. No improvement. Decided to systematically disconnect each coil and start in an attempt to diagnose the bad cylinder. All seemed pretty much the same, but ran best with #1 (assuming, as I was, that #1 is closest to the cam gears) disconnected. Baffled still. I'm starting to wonder if VADIS would show different information on the code.

Disconnected battery for a bit, which cleared the Check Engine light, but the car ran the same. Check Engine has so far not re-illuminated. Cleaned the MAF sensor. Same.

Haven't checked all the plugs yet, but will do that tomorrow-- althought a sudden onset of the condition would seem to rule out plug issues, wouldn't it?

I'm fairy baffled here. Trying to avoid a dealer trip if I can. Anyone have similar issues or any ideas?

Thanks!