I Have a 1990 Subaru Loyale Wagon and when i start it up it runs fine but after a while it starts to idle really low like 500 and below. i was having a problem with it over heating down the highway and had to limp it home by driving then letting it cool off. i found out it was the thermostat, it was all magled and messed up. so i just took it out. my car runs colder but it doesnt over heat. so does anyone know what might cause it to idle low. i was thinking timing or something like that but im not sure.

90 loyale, most likely a spfi motor right?

sometimes the idle air controll valve will do this to you, sometimes it makes it idle too high. you can try some carb cleaner down the throttle body, and the iac hose, comin right off the tb.

 

i heard you can adjust idle too, but not sure.

you might unscrew the IAC from the top of the thermostat and see if it has any junk stuck in it.

thanks a lot i will have to try that