I have a 1989 honda accord lxi (125000 mi), the idle is fluctuating from 700-2000 rpm when the engine is warm. When it is cold it idles @ about 2000. Is there anything I can do or should I take it in for service. Also it does this intermittantly.another problem I have is that when the idle is normal and I turn the fan on or hit the brakes the idle drops below 700 rpm and is really rough. Thank you for any help you can give

. Clean the Idle Air Control Valve (IACV):

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-7.html#post1054149

. Replace the Ignition Control Module (ICM) and coil:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-4.html#post265896

See if this explains your situation:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-3.html#post260436

I recommend replacing the ICM and coil every 120,000 miles or 10 years, whichever comes first. The ICM, particularly, is a problematic component.

. Adjust the idle speed to spec.

. Read this link, if the problem persists:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-7.html#post842969

Carefully read Section 5f and other information on Alternator FR Signal. It may indicate the alternator needs replacing.

It might also be a big vacuum like like the power brake booster diaphram.