Jerking 99 Windstar

My wife's Windstar at normal acceleration starts to jerk. Slam the pedal down it stops. let off on the accelerator it stops. I put it in neutral and pressed the accelerator slowly and as it reached about 4000 rpms it the engine started jerking around. Is this a PVC problem or a vacuum hose problem. Pleas someone help I am going NUTS!

Are there any engine code lights??

Is the alternator putting out sufficient voltage ... 14v+ ??

And could you be more specific ... is the engine jerking, or is the driven vehicle jerking? Does the engine "jerk" when the tranny is in Park?

I do not have any codes. The check engine light has been on for a while now. When I put it in park and press the accelerator it revs fine till it hits about 4000 RPMs and starts missing. It misses enough to make the entire engine start to bounce around. I have replace the fuel filter and the plugs and it still does it.

You must get the codes read ... or else you will be forever guessing. As you probably know, AutoZone will read them for free ... be sure you get the actual code, not their interpretation of what needs to be replaced.

Also look at the IMRC actuator and see if the little bushings are in place on the linkages.