My magna TS is idling extremely erratically. Ever since I ran the battery flat. I have read around these forums and get the impression that it is highly likely that the ISC motor is stuffed. My question is, if I source a 2nd hand one from the wreckers, is it relatively simple to take out my old one and install a replacement? Are there any pitfalls I should like out for? It seems straightforward from what I read in Hynes manual.
Appreciate any answers.
cheers

how long has it been like that? tried letting it idle for 10-15 minutes?

It has been erratic for several months now. It idles too fast, fluctuates from 1000 up to 1900. Ocassionally it goes below 1000. I have turned down the idle screw as far as it will go and this helped a but, but still idling too fast.

I think you will find that this actually the air control valve, I have seen several like this now and is getting more and more common

Can the air control valve be replaced easily?

Doesn't sound like ISC. This usually gives you a low idle when the engine is hot, but not major fluctuations.

Pull the ISC out, and check all 3 coils for continuity with a multimeter. If they're fine, open it up, give it a clean out with WD40 and put it back in. The coils are all that really goes wrong with them. After that, ensure the Base Idle screw is set correctly. Make sure the inlet manifold is reasonably clean too, it the holes that go to the ISC are clogged, that'll give you problems of course.

I sourced a 2nd hand ISC replacement and swapped it over. It is no longer idling erratically but is constantly idling at 1000 to 1100 which is too high of course. So the ISC replacement fixed the fluctuations. It sounds to me that, as mentioned by the poster above, the inlet manifold is dirty. The idling screw is set as low as it'll go - can't reduce the idling that way.