Here in Fairbanks, Alaska we are currently "enjoying" some cold weather down in the negative 30s. My 95 Legacy (AT) with 191,000 miles runs great when it is warmer that -30, but at this colder temperature the brakes frequently will act like the engine is off, and then suddenly be near normal. This does not seem to be normal even at this temperature. I have to press real hard and there is little braking. Fortunately no close calls yet. At warmer temperature when it is warmer than -20 it will do this first thing in the morning and then be normal the rest of the day.

I'm also getting a misfire code for cylinder 2. A few weeks ago when we had our last cold snap I got a misfire code on cylinder 3. The plug wires looked old so I checked the resistance and one wire was real high so I put on new NGK wires. Last summer I put in new NGK plugs. At warmer temperatures I don't get this misfire. At 2500 rpm the misfire appears to go away but at idle it comes back.

Brake problem is a frozen check valve in the booster line. I've had it happen on most of my cars, and have had good luck cleaning it. Pull it off from the booster, and squirt some MAF or Carb cleaner in there, let it sit for a minute and then start the engine, and spray some more through there with the engine running.

"Correct" fix is to replace that booster hose.

 

As for your misfire. I'd throw a set of NGK Copper plugs at it, their cheap and easy for that engine...

Thanks! I'm not sure where the check valve is or the booster line. Will this require bleeding the brakes? My plugs are the standared NGK plugs recommended for this engine (BKR6E-11). Are those the copper ones you suggested?

No bleeding required, this can be done in about 3 minutes with just a pliers. It's in the rubber vacuum hose between the engine and brake booster (if you need more info, google some of those terms and all your questions are answered, this stuff is used on all gas engines with vacuum boosters).

Those sound like the right plugs. Are they fairly new? 

Check for hairline cracks in the ceramic-insulator of the spark-plug for the misfiring cylinder.

A hairline-crack is hard to spot, but can allow leakage of high-voltage pulses, and might be giving you the misfire code.

2 hours ago, Numbchux said:

No bleeding required, this can be done in about 3 minutes with just a pliers. It's in the rubber vacuum hose between the engine and brake booster (if you need more info, google some of those terms and all your questions are answered, this stuff is used on all gas engines with vacuum boosters).

Those sound like the right plugs. Are they fairly new? 

Yes, installed in 2019.

in light of the recent revelations about "fake" plugs, where did you buy your plugs from?

ebay or a proper parts store?

if from a proper parts store, they should be ok, but doesnt hurt to check them anyway.

if from ebay, they could be questionable.

17 hours ago, heartless said:

in light of the recent revelations about "fake" plugs, where did you buy your plugs from?

ebay or a proper parts store?

if from a proper parts store, they should be ok, but doesnt hurt to check them anyway.

if from ebay, they could be questionable.

I got them from Rock Auto, an online business. Are they considered reputable? Anyway, yesterday afternoon after work, my car had been plugged in for 8 hours. Standard winterization here is an engine oil heater and a block heater. Some cars also have a battery warmer and and heater for the Automatic Transmission fluid. So it started nicely at -38 F with no misfires. It had been plugged in for 4 hours before I started it yesterday morning. So it seems to like the 8 hours of plug-in time much better. So I plugged it in last night for about 8 hours. No misfires this morning. Also it has warmed up to a balmy -30.

23 hours ago, Numbchux said:

Brake problem is a frozen check valve in the booster line. I've had it happen on most of my cars, and have had good luck cleaning it. Pull it off from the booster, and squirt some MAF or Carb cleaner in there, let it sit for a minute and then start the engine, and spray some more through there with the engine running.

"Correct" fix is to replace that booster hose.

 

As for your misfire. I'd throw a set of NGK Copper plugs at it, their cheap and easy for that engine...

I put the legacy in my heated garage after work yesterday and took off the brake booster line. But I did not catch the part where you said the valve is in the rubber hose rather than where the hose connects to the black contraption on the firewall. Anyway I sprayed some MAF cleaner in there and in the engine manifold, but not in the hose. Anyway, some of the MAF cleaner must have ended up in the hose since there were no braking problems this morning.

2 hours ago, Ravenwoods said:

I got them from Rock Auto, an online business. Are they considered reputable? Anyway, yesterday afternoon after work, my car had been plugged in for 8 hours. Standard winterization here is an engine oil heater and a block heater. Some cars also have a battery warmer and and heater for the Automatic Transmission fluid. So it started nicely at -38 F with no misfires. It had been plugged in for 4 hours before I started it yesterday morning. So it seems to like the 8 hours of plug-in time much better. So I plugged it in last night for about 8 hours. No misfires this morning. Also it has warmed up to a balmy -30.

yeah, Rock Auto is usually ok, i do a fair bit of business with them, too, but not for sparkplugs. Those I usually buy locally

 

11 hours ago, Ravenwoods said:

I got them from Rock Auto, an online business. Are they considered reputable?

Absolutely reputable. I, and many others, buy from them all the time and they post discount codes on this forum regularly. 

they’re a reseller of product, they don’t make anything. So they’d have the same parts any local store carries, and much more.  They can’t verify or QC all of their suppliers so any issues with a supplier could be seen through rock auto just like any other store you buy from.