I have a 2001 Windstar 3.8L. Sometimes when I start it up it will misfire and stall out, other times it will idle really rough but if I give it some gas it clears up and runs fine, and other times it's completely fine from the start. This happens on cold starts and after I've been riding around all day. The engine light has never come on but I had it check anyway just in case I missed it, no codes.

It just had full a tune up last august, new plugs, wires, cap, air filter.

With no codes and all the basics covered I don't know where to look next.

 

I would have clean the injectors. I notice when the injectors gets dirty the gas doesn't go through that well and idles or misfire. that's my experience in mine. I hope this helps.

Gabbs

 

In your spare time, you might look around the engine for a loose , cracked or questionable vacuum hose, especially the one with the PCV valve on one end.

 

Once you make sure you have the wires connected in the correct firing order, you should check to make sure there is voltage coming from ignition coil THROUGH each wire. I simply use a basic digital voltmeter. You will most likely have to use the lowest setting, in millivolts DC. The digital voltmeter can still detect the voltage through the insulation of the wire. This will determine if the ignition coil pack is working properly for all cylinders. You might discover one cylinder is not firing properly as compared to the others. What you want to do is compare all the cylinders and get an approximate voltage for each coil. I typically read about 0.25 to .50 millivolts through each wire. It will fluctuate, since the voltmeter is really sensitive but as long as you know there is voltage coming from the ignition coil to each of the spark plugs is good. I used this method to discover I had a bad ignition coil when one wire only read about .00 to .05 millivolt (viturally no voltage). Do this at your own risk, since you have to do this while the engine is running.