windstar bad hesitation

I have a 98 windstar everything running great except for an alternator.. however today I pulled out and had no power hard time getting to 40 mph. After that everything ran fine. It seems like after I shut it down for a little it runs fine until about 20 miles then it acts up again. Could this be a semi clogged cat. please help. Right now van seems to be running alright. But I dont know for how long. It did seem like after I reached the 40mph mark it straightened up. Also when it does act up I press the pedal the whole way to the floor and still no power.

gbetteley (http://www.automotiveforums.com/vbulletin/member.php?u=470019)
Need a little more information. Engine size Miles. Any codes?

Haveing had a bad hesitation problem my first suggestion would be to check the fuel pump. If you do a search you will find lots of information on this.

My first thought was also clogged converter. Has the pump been replaced before? Let us know if you have the ability to diagnose. You will need a fuel pressure tester. There are some simple test and things to check give more info and search under hesitation.

It is a 1998 Windstar. It has 135,000. I dont know if pump has been replaced or not.It does have a cel code for o2 sensor bank #2. I'll explain further I pulled onto bridge and had bad hesitation. Around 40mph it regained power. It was alright until I stopped then again same problem pedal pushed to floor no power. Then after shutdown and restart it was alright for rest of night.

I am wondering if the bad alternator could be causing the problem......above 40mph....maybe it is spinning fast enough to give you the voltage that you need.
A lower voltage will cause a lot of issues......
So....I would replace that......as you know it needs to be replaced.....then see if other problems are still there.

I would also check the battery.....as a battery can cause a extra load on the alternator......causing the alternator to fail over time.

sorry must of messed up on typing alternator was replaced 4 days ago before this problem started.

gbetteley - My recent extremely fun experience (lol) with testing my old Cats may lend some help if you want to test'em - Thread: Bad car or not (http://www.automotiveforums.com/vbulletin/showthread.php?t=893327)

If you order the tester I did note that after the test to get the vac tube off the adapter you'll have to twist it off like a screw and/or cut it as the heat completely crystallizes the rubber vac tube where it meets the adapter. You'll see what I mean in the thread.