Surging at 45-50mph, Trans? Did troubleshooting. Need Help!

[JSimp]

Sorry if people have had similar problems but I searched and searched and have not found anyone with a problem similar to mine. There have been several with other issues that seem to be different from mine. Here are the details:
2007 Explorer AWD 4.6L v8 95,000 miles.

Driving fine until about 45-50 mph cruising when the rpm's jump between 1250-1500 depending on the speed. Its typically only a few hundred rpm jump and when I accelerate it goes away, it has a forward surge feeling when it jumps. Seems to be a problem at slower speeds as I can see the rpm's jumping but always around 1250-1500 rpm and no feel of surging.

I have checked all coils which are within limits (all arount .9-.8) and boots all appear to be in good shape. Replaced the TPS (due to it always surging in the same rpm range) which failed to correct the problem. If i turn OD off it appears to not jump around.

I am at a crossroads here thinking there might now be a problem with the tranny or OD or torque convertor? I have to tow 2 motorcycles tomorrow about 200 miles round trip. At highway speeds it appears to be fine. Any ideas anyone! I really need some help. Thanks

 

[Phisherman]

Try this if you haven't yet. http://www.explorerforum.com/forums//showthread.php?t=416013

 

[Bklein711]

Did you ever figure out what the problem was? I'm having this problem now after installing a Throttle Body spacer. Dealer says I need to replace the throttle body. I think that is BS, I'm not buying in yet as to that being the issue.

The ex ran completely fine after the install and the next day started surging when at a stop or trying to accelerate. Everyone in a while though it accelerates fine with no issues. What is wrong?