acceleration problem

[Trons]

Ok, I had just gotten done replacing the intake manifold gasket, the plenium seals, The front IMRC, the IAC (Yes, it was bad), cleaned the MAFS, changed the fuel filter and air filteron a '98 windstar with the 3.8l, and the Van ran great, for about 2 days. I had to go back and redo the thermostat housing gasket because it was leaking. I test drove it and it seemed good, the next time my wife drove it, it sputters on from stop to go acceleration.

It idles great, and if you push the throttle very slowly there is no problem. The problem only manifests when going from idle to about 2k RPM whether its under load or not. I've checked all my connections and vacuum lines (I believe) and I can't seem to find anything wrong at this stage. when this is going on, there is also a popping noise that sounds like it's coming from below the MAFS.

Any help with this problem would be even more greatly appreciated then the help I have recieved thus far...and that's pretty darn appreciated.

Trons

[12Ounce]

I gonna guess "ignition". Start by checking all plug wiring to make sure you didn't knock something loose ... or did you leave some extra grease or something atop the ignition coil. ???

Use a length of hose as stethoscope to better locate the popping sound.

Use that same hose to listen to all fuel injectors .. to see (hear) that they all click the same.

[dmoltrup]

My guess is the vacuum line(s). I just bought my van and it had the same problem. The shop owner went through $800 in repairs before finally bringing it to a Ford dealer himself. The dealer "fixed" the problem, only to find it doing it again before returning the van. Finally, they replaced a vacuum line and it went away.

[Trons]

Update:

I've been beating my head against the hood of this thing for the last several days because of this problem. I've replaced the IAC, the TPS. I've had the plenium off about about 10 times checking different things. It doesn't seem to matter if it's warm or not, it does it when it's cold.

EGR only comes into effect when it's warm right? My understanding is that EGR opperates when engine temp is above a certain set point. I have tried taking the plug off the DPFE, no difference. I have taken the vacuum line off the EGR, no change.

I'm about ready to drive it off a cliff. Any help would be great...

Trons

[12Ounce]

Did you have any luck with the "popping sound"?

Your understanding of the EGR system is right, I believe. And disconnecting and plugging the EGR control hose for testing is a good idea. Why don't you now try doing the IMRC actuators the same way? It may cause a code to appear ... but would be a good test for a leaking diaphragm.

[Trons]

I believe the popping sound is actually the engine backfireing. The IMRC's? I replaced one of them, but both of them are working good, you can watch them actuate and uhm....unactuate at the same time, at the same point in the engine revolutions.

Trons