I have a 1996 Honda accord LX I am having trouble with I'm assuming the idle. I've changed the tps and the iac and it still revs up and down on its own and does a "weeooo" noise. When I drive it goes as far as I between 3 and 4 rpms and then goes back down. When I put it in park the "heartbeat" starts, when I but it in gear it goes away. I can't figure out what is wrong with it or what else it could be.. Does anyone have any ideas? Is it a vacuum leak?

 

Certainly be checking the vacuum lines regarding this. I have to assume that it is an AT given your post, but please post back with transmission type.

 

Check the fast idle control valve.. clean the plunger and tighten down the outer ring. Google it.