High idle. Engine won't slow down while coasting. No HVAC controls. P1506. Related?
I have a 98 2WD ford ranger with a 2.5L. I bought it a little over a month ago and I noticed shortly after that it was idling a little high. It seems like it's gotten a bit worse and now it idles at about 925-975 RPM. Its not a perfectly smooth idle, but it isn't too rough.
The motor also doesn't slow down while the clutch is in or while its in neutral until I come to a complete stop. If i'm at 2500 RPM when I take it out of gear, that is pretty much where it stays until the truck stops.
Also, the HVAC controls don't work. It always blows out the dashboard. Changing the temperature, speeding up, slowing down, going WOT, idling, all have no effect.
It also has a check engine light, P1506. For about two weeks it was only a pending code, but now the light is on.
Things I've checked/tried:
Clean IAC valve, throttle body, and MAF sensor
Tested the TPS. It reads .8 volts at idle and 4.75ish at WOT. Seems normal to me.
Unplugged the maf while idling. The truck dipped down to about 600 RPM for a split second, then right back up to 950. No other change
Unplugged the TPS while idling. No change.
Unplugged the IAC valve while idling. Truck drops down to about 850.
Plug it back in, back up to 950. So it seems like it may need to be replaced. I also noticed, that while it was off for cleaning, it appeared to be open slightly. I'm not sure if this is normal.
Sprayed brake cleaner on a couple vacuum hoses (I doubt I got them all, and my truck doesn't really appear to match what's on the vacuum diagram sticker) and around the throttle body and intake manifold. No change.
As far as the no HVAC controls go, I looked for the little "orb" that everyone refers to when this topic comes up, and I can not find it.
I can replace the IAC valve but I wanted to get some input first. Thoughts, tips, tricks, suggestions?
Edit: About the vacuum orb thing. The truck has larger tires, removed fender well liners, and a swapped motor (from a 99). I'm thinking they could have removed it for any one of these, and never put it back.