Rough Idle Cold and stumble at 2000 RPM

I believe I have two separate problems: My 02 Windstar has a rough idle when cold (it settles down when the engine warms up; and it runs a bit rough at 1800-2000 RPM (it's not so steady that I would consider it a miss, it just sort of "hiccups" every one or two seconds).

It was much worse last week. I replaced the coil & plugs (wires were replaced about a year ago). It improved, but not much. So I plugged the EGR line, and it got a lot better. This past week-end, I pulled the upper plenum, and cleaned out the EGR ports (three of them were closed or almost closed), and replaced the PCV. I did the isolater bolts a year or so ago, so I did not pull the lower plenum, just used a long pick and used a small tube duct taped to a vacuum hose so I could get it right by the EGR ports as I scraped.

It is much better now, but I can still feel a stumble at about 1800-2000 rpm. It is most notable in OD, but I sometimes feel it in the lower gears as well.

For the rough idle when cold, I pulled the IAC motor and cleaned it following Leckemby's directions, but the problem is still there.

Yesterday, it set codes 303 & 304 (misfire on #3 and #4).

Any suggestions on what to check next?

Of course, air leaks and the IAC valve are high on the list.

But I will include another ....the synchronizer may be getting "sticky" (dry of lubricant). The synchronizer is the thing that drives the cam positioner sensor. Its a well made gizmo that is pre-lubed with a couple of O-rings that are intended to keep the lubricant in place ... but over time, the oil dries or escapes.

It helps "some" to put a few drops of clean motor oil around the top of the spindle-shaft every 40k miles or so. Use 7/32" combination wrench to lift the sensor to access the spindle.

For best results, if you have the time, remove the screws from the sensor and re-install in the housing (this plugs leaks). Now fill the upper chamber with clean motor oil and let sit overnight. Next morning, mop out most of the oil that did not run down the spindle. Leaving the chamber wet with oil, re-install the sensor.

Thank you, 12ounce. How difficult is it to get to the cam sensor?

Not very. Even with my fat fingers, its not a bad job. You will find the cam sensor sitting right on top of the front engine cover. Only remove the cam sensor ... do not disturb the hold-down bolt for the synchronizer ....or the timing will suddenly be an issue.

Thank you. I'll add some oil tonight, then pull it and let it soak overnight this week-end.