I have 1989 Honda Civic LX sedan w/1.5L. When the car is warmed up, the engine will idle at about 2000 rpm for 30-45 seconds and then bounce up and down between 1000 and 1500 rpm. Very annoying. I have already removed and cleaned the iacv, no help... can anybody suggest what to try next? TPS sensor maybe?

. Replace ignitor and coil.

. Read link below:

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

Thanks TX, I have a question for you, are the ignitor and the ignition control module the same thing? I replaced the ignition control module almost a year ago per your advise as I had a problem with the car shutting down 10-15 minutes after starting. It has been great ever since then until a few months ago when it began this irratic idle problem. This car performs flawlessly 90% of the time as I drive it 90 plus miles a day, get over 39 mpg overall, until it comes to idle... then the engine holds a steady 2000 rpm, then does the up and down thing between 1000 and 1500 rpm. Sorry to be a pain, but I appreciate your advise.

Yes, they are the same. When you replaced the ignitor before, did you apply a thin, even coat of heat transfer silicone grease to the back of the module? If you don't, they won't last long.

If that's not the problem, check for vacuum leaks.

I would say that if your sure the ignition module is good than its deffinately a vacume leak

Thanks guys, I did apply the grease that was included in the box with the module, however, I guess its possible that it could have gone bad again. I'm not expericencing any stalling problems like before, just the idle issue. I'll start over again checking the hoses for any vacuum leaks. Any suggestions other than taking each hose off one by one to check for the leaks/cracks?

Unfournately vacuum leaks are just as difficult as they seam, try listening very carefully, if you have something that can some kind of steam, you can sometimes use this and you may be able to see, check areas that are exposed to a lot of heat first, as those are more common to crack, after check the area where you did work last. And so on...

Let us know