How do you know if the throttle actuator is bad? I usually have a very hard time starting my car (when cold) and once it's started, the idle is way too low....around 450-500, and sometimes 350 or so. My cruise control doesn't work most of the time either.

Of course, there's once or twice a week when I start the car, and it idles perfectly around 1000 when cold and slowly decreases as the car heats up. The cruise works perfectly in these conditions.

I'm wondering if it's the throttle actuator, or (hopefully) something else that could be causing these symptoms. How do I rule out a bad throttle actuator? And isn't it kind of strange that everything can run perfectly one day, and terribly the next? Maybe a lose wire or something?

Thanks for the input.
Matt
1994 E320
150k