I'm working on my brother's 95 Toyota 4Runner. 3VZE, Auto transmission.

I've got an odd issue. It starts up idling low, like around 700 RPM. It then gradually rises as it warms (also warms up slow). It will then settle at about 1300 RPM. Obviously, this isn't right.

It only has 95k miles but it has cooling issues. The old coolant was FILLED with rust, currently flushing the system real good. No vacuum leaks, everything is hooked up correctly as far as I can tell. Also, the heater doesn't work, thinking it's clogged up with rust and such.

I'm about to check the TPS and ECT to make sure they are in spec. Not sure what to think though, I've never seen one do this. Also, the idle speed screw is lowered as far as possible. If it put it to where my truck is at, it idles at like 2000 RPM!

Any ideas are welcome.

 

Mineral build-up on the coolant sensor feeding the ECU?
Bad thermostat fouled with rust?

 

Thermostat was ok, forgot to mention.

TPS was installed wrong, was way out of whack. I'll see if I can pull out the ECT.

*Edit* TPS made no difference.