idle problems

[anchovies]

Okie, I've adjusted my idle to 750 and most of the time it stays there. But sometimes it might go up to 1000 and stays there (it's not going up and down, it just idles at 1000 when I need to idle) and sometimes its 500.

What am I looking at here?
Thanks, appreciate any help and input.

[Immeraufdemhund]

Do you have anything turned on that would take power? (example: AC)

[1989se-i]

My idle is fucked too. It was @ 500, then i upped it to 1K. Now its back down to 500 and it idles really rough.

[anchovies]

No AC no power robbing accessories either.
The car is driven under the same conditions (not weather condition!!)

[smufguy]

sounds like ur coolent sensor is fucking up. on the carbs the thermo valves have the mind of their own and mine was like that. when i had my carb in and working, the thermo valves said that the coolent was cold and the next minute they said they were warm so the idle just roughened as time progressed. there was a thread about the same prob concerning the idle. check it out, sorry i dont remember which one it iwas

[anchovies]

If the ECT is at fault, then why is the idle going lower than normal. I understand it going higher than normal like when you first start the car, and ECT might be doing it at other times also when the car is already hot, hence the up idle.
I might be wrong...hmmmm I think my ECT is about 1/2 year old though.
What else? It's not intermittent.