3.8 SXT - Grand Caravan (75K miles): Cruising on level road at 65 mph transmission jumps from 2K rpm to 3K. I let completely off the throttle and it stays at 3K for a few seconds and then with a clunk goes to 4th gear and back to 2K rpm. Lightly stepping on the throttle and it goes back to 3K and sometimes jumps up to 4K. It even jumps like this going downhill if there is any throttle applied. It really goes crazy with the cruise control on.

I stopped at a dealer and they read no codes. They did something to reset the transmission computer map (reflash maybe?) and the problem was gone for most of the trip but it did jump up a few times.

This problem occurred again on recent trip so I pulled off the road and the van idled at 2K and not the usual 700 rpm. I disconnected the battery for a while and got back on the road and did not use cruise control the rest of the way. It did act up a few times over the course of 6 hours. I even tried filming the tach to show what was going on but it was like the van knew it and would run fine. Maybe I need to keep a camera running all the time!

I would like to know if anyone has experienced a similar problem and what the cause might be. I suspect a computer issue.

My current other problems:
A. Air bag light comes on sporadically
B. Power locks stop functioning sporadically
C. At idle rpm's suddenly drop to a near stall - yes sporadically
D. Clunking front end suspension

 

This sounds like an electrical problem.
Look for loose grounds,dirty battery connections,loose plug connections,and corrosion around any electrical connection.
With my limited experience I'm going to say there is a loose connection somewhere fairly close to the battery.The reason I think this is because of the seemingly unrelated list of problems.If it was only the idle or the transmission I would say there is a bad sensor somewhere.With no codes showing up I'll stick with the loose connection.
The sensors are getting faulty information through crazy voltage changes and forwarding this information to the computer.The computer then tells the functioning system to do something that it isn't supposed to do and you have the transmission shifting at improper times or the engine racing away.
If you can get a Haynes or Chiltons manual they will have schematic diagrams of the electrical system.You could use this to maybe find a common connection for some of the faulty systems.They are only around $20 and have a lot of good info.

Here's a good link also.http://www.allpar.com/

 

I do have a Haynes manual and will take a look. The battery is relatively new and the connections are clean. I disconnect the negative terminal regularly to reset the locks. I realize this is difficult to diagnose in a thread but I wanted to see if anyone has had a similar shifting problem before I let the dealer start chasing ghosts. Thanks!

 

I am having the same problem with my 2004............brought it to the trans shop couple of times..they say no codes I had them change a module to no luck. Van still does it once in awhile.... Did you find out any more info ?