It idles rough at 500-600rpm.changed out both O2

Have you checked/replaced the O2 sensor(s). They produce the data that your computer reads. Bad/clogged O2 sensors will trick the ECU into running lean/rich.

Three things you should check using a good code checker which can read sensor outputs - the throttle position sensor (TPS), the mass air flow sensor (MAF) and the EGR valve. While you are at it, replace the PCV valve.

For rough idle and error code issues on your ford freestar.Click the link below:----
http://howtobyme.blogspot.in/2012/01/2004-ford-freestar-van-idles-rough.html
--------This will help.Thanks.

Dirty fuel injectors.

As long as everything you've mentioned is in good working condition I would test your O2 sensors and your mass air flow sensor both could cause a rough erratic idle and even a miss if the O2 sensors send a bad signal to ecu which would affect fuel trim ratio

Did you install new spark plugs? Definitely replace the O2 sensor.

could bea few things. Excessive moisure, low fuel pressure, Faulty coil pack, spark plugs gap or wires. Have you changed any of those at all? Let me know

well i'm sorry that you got the miss information here on fixya. because all internal combustion engines need a pcv valve to operate properly.

now the information you got first is correct and pcv valve can set false codes like o2's and lean bank conditions also can cause you vechile to run or idle rough.

no there are a few different styles pcv valves and some times don't look like your convetional pcv. some are heated in different ways either by coolant ( witch look like a conventioanl pcv but with a coolant tube around them) then electricaly heated and they don't look like them at all. but one thing that has to stay the same is the pcv valve has to ventilate the crank case and will be found somewhere on or near the valve cover because it is the easiest and most accessible point of the engines crank case area. so i would look for that and usally on that vechile it is on the passanger side valve cover in the middle.

with that said and seeing you did all those repairs i would go right for that as my next step. but there is other thing that cold cause this issue like leaky injectors and is almost more likely becuase of the o2 sensor code and backfire. do you have the code # so i can look it up and best assist you?

see vechiles are hard to fix over the computer as i am trying so if you have any more question/info about this issue please ask and i will be glad to help.

the speedo gear is in the tranny in that model i believe so thats a seperate issue..

to the rough idle, it could be a multitude of things. the MAF could cause it, you can get one online for cheap. cleaning it is sometimes not enough.the o2 sensors do one thing, that is tell the ecm how much fuel is being burnt in the cylinders, if it is too rich it leans out, if it is too lean it gets rich..

put the vehicle into drive with your foot on the brake, slowly give it gas if it revs like normal it is a spark/ignition problem, which can also be low compression. if it doesnt stumble and run bad with a load on it it is most likly a fuel issue. you have to rememeber that if the o2 sensor is bad, it will cause a misfire by pumping too much fuel into it. try a compression test, remove all plugs, screw in tester, crank engine, record psi. if the psi is lower than %15 of the highest rating then the cylinder has low compression. add a teaspoon of fresh oil into the cylinder and repeat test. if the compression goes up the rings are faulty. if not it could be a bent valve or somethign along the lines of a valvetrain problem.. good luck

try changing distributor cap & coil