1990 bonneville idles around 1000 but sometimes it will drop suddenly to 500 for a split second almost die the right back to normal? cleaned tb changed the iac, air cleaner, fuel filter, plugs and wires look good changed some vac lines, not pulling any codes Cant afford to change random parts does anyone have any other suggestions. thanks Dale

Check and make sure none of your spark plug wires are near a ground or the O2 wire in back. Check your battery cables and make sure they are clean.

Thanks i'll check it out let ya know gotta go to work for now

I checked battery cables looked at plug wires and how they are routed o2 wire is fine still having the idle drop it does it at least once a day if not more. it usually doesnt die so its no real big deal but it really annoys me I cant afford to take it to my mechanic he'* really cool about advice and looking at things. Thanks for the help ideas.