2008 2.3L Low idle/Stall
I have a 2008 Ranger XL with 2.3L I4 with 69,000KM.
3 days ago it started having a low idle(4-500RPM) and will stall out due to the extremely low idle. If you hold 10-20% throttle it will start and run no problem and is drive-able until you have to stop at a light and it will stall. It does not appear to be down on power while driving it like this and after it is warm it will actually idle without stalling but still a low idle at 5-600RPM.
The weird thing is it has also run perfectly fine a couple times after this has started. I drove it home from work idling low, went inside to change and came back out to work on it and it fired up completely normal and idled perfectly. Same thing when I went for lunch the next day.
I have occasionally had a high idle in the past as well, up to 2000RPM, but only during extremely cold winter days, and usually only after a long highway drive. When coming to a stop it will stay revved at 2k RPM until you come to a complete stop and then drop to regular idle.
It has a fresh air filter. I have checked the resistance on the TPS sensor and it seems to be ok and not spike. I have checked the resistance on the IAC and it checked within spec. I unplugged the IAC while the truck was running and it made a noticable drop in RPM which leads me to believe it is working correctly. I have unplugged the battery to reset the system. Battery sits at 12.7V and 14.4V at idle.
The only thing I have recently changed is the battery about 3 days prior to this beginning to happen. I can't see it being the root of the problem but I plan on taking it back and having it tested just to be sure. It cranks strong and seems to have a good standing and idle voltage.