2002 Windstar hesitation during load

Can anybody help me? I have a Winstar that hesitates during acceleration. Usually when I am trying to get on to the interstate. I can also get it to stutter at about 3500 RPM right when I start it cold. It goes away if the engine is warmed up. Here are some of the things I have tried. I replace the plugs and wires. I replace the intake manifold bolts and gaskets as per TSB # 03-16-1. (Yes, I did have an engine light and error codes 171 and 174). While I had the intake manifold off, I cleaned the EGR orifices. I also replaced the tension pulley and idler pulley because the bearings seemed worn out. I thought one of them may have been locking up at high RPM. I checked all the vacuum lines. The vacuum is a steady 22in Hg at idle and during the hesitation. I replaced the inline fuel filter, I also cleaned and tested the fuel pump relay. I poured Sea Foam into the intake through the PCV port twice, just like another TSB recommended. I did not bring the van to a dealer to have the timing changed. The TSB was for knocking, and I don’t hear any knocking.
The next thing on my list is to change the fuel pump. I checked the pressure with a tire pressure gauge, and it read 30 psi at idle. This seems fine… I also ran a tank of fuel injector cleaner through the engine.
It looks like I will have to bring it into a dealer, unless you guys can give me some more ideas.
Thanks in advance

Can anybody help me? I have a Winstar that hesitates during acceleration. Usually when I am trying to get on to the interstate. I can also get it to stutter at about 3500 RPM right when I start it cold. It goes away if the engine is warmed up. Here are some of the things I have tried. I replace the plugs and wires. I replace the intake manifold bolts and gaskets as per TSB # 03-16-1. (Yes, I did have an engine light and error codes 171 and 174). While I had the intake manifold off, I cleaned the EGR orifices. I also replaced the tension pulley and idler pulley because the bearings seemed worn out. I thought one of them may have been locking up at high RPM. I checked all the vacuum lines. The vacuum is a steady 22in Hg at idle and during the hesitation. I replaced the inline fuel filter, I also cleaned and tested the fuel pump relay. I poured Sea Foam into the intake through the PCV port twice, just like another TSB recommended. I did not bring the van to a dealer to have the timing changed. The TSB was for knocking, and I don’t hear any knocking.
The next thing on my list is to change the fuel pump. I checked the pressure with a tire pressure gauge, and it read 30 psi at idle. This seems fine… I also ran a tank of fuel injector cleaner through the engine.
It looks like I will have to bring it into a dealer, unless you guys can give me some more ideas.
Thanks in advance Chances are that the IMRC are not working because the 2 actuator are disconnected or desapeared, the 2 plastic connector broke and the rods that acrivate the manifold baffle are disconnected or missing. This is a common problem on the 99 and later model. Normally you have to disconnect them when you have to remove the intake manifold ( when you fix the 171/174 problem)
The IMRC (2) are electrical (receive information from the ECM) on your model and they activate the manifold baffle over 3000 RPM. This could be a cause of poor acceleration over 3000 RPM specially with a heavy acceleration like you have mentionned here. (3500 RPM engine cold)

OK, I finally had a chance to look at the van this weekend. I checked the linkage to the IMRC module. It is connected. A few weeks ago, I did find one of the clips broken and replaced it.
I can rev the engine while in park, and get the IMRC to open and close at about 3000 RPM.
Still no engine codes showing up. The van still hesitates like it looses spark or fuel while under load. I have seen it happen as low as 2100 PRM when the engine is cold.
What are the symtoms of bad fuel injectors?

I will try a tank of premium gas to see if it helps. I will let you know.

Okay I'm back. I still have the hesitation under load when the engine is cold.
I changed the coil pack and Ohm'ed out all the coils between the new and old one. Both had an average resistance of 10.2K ohms. I was hoping the coil would help, but it didn’t.:banghead:
I ran another can of B-12 through the engine. I also ran another tank of high octane through to see if it would help.
I went out a bought a fuel pressure gauge with a long hose so I could watch it while I drove. It registered 30psi at idle, 40psi with the engine off and the key in the run position, under load, it stayed around 32psi.
On a side note, I replaced the power steering fluid with synthetic transmission fluid and for the first time in years I don’t hear the high pitched whine when I turn the steering wheel.
Are there any other ideas out there?

Try cleaning the mass air flow sensor. Sensor is mounted in the air filter housing just downstream of the filter. It is protected by a screen. The part to clean are the two resistors suspended by thin wires, cleaning the connector is adviseable also. Use the special MAF cleaner, non residue type. In another thread, the CRC brand cleaner was not recommended. Seems like hesitation is most prevelant when engine is cold. While your poking around check the resistance of the intake air temp sensor at the throttle body. According to Haynes, resistance should be about 37,300 ohms at 68F and decrease after engine warms up. Resistance checks made with engine off and connector unplugged. Manual also states that there should be 5 volts at connector with key on engine off. The engine coolant temp sensor could also be checked, the temp sensor with a two wire connector. Again about 40,000 ohms at 68F decreasing to about 3000 ohms on a fully warmed up engine. Although sometimes I have found that resistance values work the exact opposite of what the Haynes manual states (throttle position sensor).

Here is a link to a picture of the MAF sensor on my '96 3.8L.
The "+" is where you want to spray the non-residue electronic cleaner.
Hold the MAF sensor so that you are looking down into it....and the plastic "bar" is sloping downward slightly away from the hole that I marked with the "+".
This will get the cleaner over the resistors inside the "bar".....and it will run out the hole on the other side.....and end of the bar.
The next picture is a view from the throttle body side....and shows the hole that the air comes out.

http://rides.webshots.com/photo/1350023782011220610bXQOkA


Next, is a link to a picture that shows the Input Air Temperature Sensor.
You can clean it with the same spray cleaner as the MAF sensor.
http://rides.webshots.com/photo/1350063274011220610OBlGGb

If you have a oil type air filter, like the K&N, it is common to get some oil film onto these 2 sensors.
The oil film.....or dust will be flushed away by the spray cleaner.