Time to pull the plugs and wires and look for carbon tracking.

heater circuit codes dont monitor engine variables really its just warming a resistor and monitoring it for electrical faults. if it was a rich or lean code i would say yes, but it seems most likely to be two separate issues if i had to guess

True on the O2 sensor, right now it'* too cold and snow is blowing everywhere so I'm going to unplug the MAF sensor tomorrow just to somewhat rule it out. The car clearly has only city kms or wasn't driven much so I have a list of things I need to change and spark plugs is definitely one of them as I'm sure there'* a lot of carbon buildup on them, which may be contributing to or be the cause of the issue.

I feel like the thermostat may also need to be replaced as it is either stuck open or very slow- after 10 minutes of steady driving at around 60km/h it'* still cold or at 1/4. After maybe 15 minutes it'* all good and hovers just under the 1/2 point. But, it only takes a few minutes for heat to blow so I'm not convinced there'* a problem.

could need replaced. you would think it would warm up faster than that, even in the cold weather

So I unplugged the maf sensor and the problem seems to have disappeared, it was -22 C out early this morning and aside from a lot of smoke it was running great and did not hesitate. Just started it up now and the problem is gone.

The only thing I've noticed is poor highway gas mileage - no more than 20mpg.

So far it'* either the maf sensor that'* the issue or unplugging it may have helped a different issue?

unplugging the maf or a bunch of other sensors puts it in open loop which runs off a preset fuel and timing table, sort of a limp home mode. it just makes the engine run

I know it'* practically impossible to diagnose this kind of issue properly over the internet but would you say it'* worth my $26 to replace it and see if it'* fixed before replacing anything else? I reset the codes in the computer and the only ones that came back were something about the MAF sensor voltage.

I put some fuel system cleaner (Mr. Gasket Cataclean) in and it stalled immediately after starting it up (engine was still warm) but there were no more issues after I started driving it to run it through the system.

I may give cleaning the sensor a shot before I buy a new one, considering the buildup on all of the other parts it'* likely the MAF is clogged up

if you are talking about the o2 sensor, its alot more often the sensor is bad than the wires or plug, but its very easy to check as i said all you have to do is check the voltage. the o2 codes take a while if you have a scanner that has i/m monitor scanner check to see if the o2 or ho2 has gone ready

as far as the maf its expensive so i would try cleaning it first and see what happens, make sure you use maf cleaner only.

Next thing I'll check is the O2 sensor, I have the MAF sensor out for cleaning (I went out and bought MAF sensor cleaner), there was definitely some fuzz on there and I sprayed everything out and I'm going to put it back in tomorrow morning (it'* too cold out right now) and see what happens.

While I was driving it today the car actually stalled on me (fortunately I was coming to a light so I didn't have to steer), but I'm going to blame it on something due to that combination of missing maf sensor and the fuel system cleaner.