rythmic engine pulsing (slight) at idle 2001 windstar

This may be my last post because probably going to sell the deathstar after 6 years of ownership.

Here is what is happening. At idle RPM range (parked, or at stop light, etc) foot off gas.

Engine pulses at a steady even rate about every second or so not really noticible on the tach, but you can hear and feel it. Coincidently after I put on a salvage yard power steering pump a few months ago I started doing this, but I was led to believe it wasn't related.

A guy at work is describing a sensor that adjusts idle for power steering when you are stopped or low rpm to allow for extra power when you are at low to prevent it from bogging down.

put on a recent alternator as well, but that was new. Also did the P171 etc repair already, changed plugs about 2 years ago, and wires more recently, ignition coil recently. cleaned IAC all the time....

Any ideas?

Well - the "sensor that adjusts idle" is indeed the IAC. Maybe it's time for a new IAC instead of cleaning the old one (though I'll note my '00 Windstar still has the original IAC at 145K+ miles; it gets cleaned regularly).

Other common causes of Windstar idle problems are related to vacuum leaks. Any possibility the power steering project loosened a vacuum fitting?

x2 on the IAC. That's a simple, quick procedure that, if not recently done, should be anyway. I know what you refer to regarding the ps pump calling for increased rpms when low. You could diagnose if it is the pump by simply letting the van run at idle, and standing on the outside of the van with the drivers window down just slightly turn the wheel. If you catch it between the rhythmic idle you're having you could see if it's adding to it or not. It is normal for the rpm to jump from turning the wheel at low rpms tho so that's fine. Take a look at the state of your air filter too.

I'd be cleaning the IAC and bet your problem leaves. Just make sure to get IAC cleaner so there's not residue left on it.

surprising to no one... i cleaned the iac again and it helped!

I think iac cleaning should be done at every freaking oil change on these things.

I do have 180k+ on the original, but it has to last me a few more months.

Well, I'm pleased that (yet another) quick IAC cleaning did the trick for you.

Yes, regular cleaning is a good idea - though, at 180K, it's likely due for replacement - if you were hanging on to the van.