Strange shifting issues

[Dr.Evil]

Hoping I can diagnose this without taking it to a shop. Its a 2001 with rebuilt 4R100 that has around 80-100k on it. Truck ran fine one evening, then the next morning it started shifting strangely. It feels like it surges a bit on upshifts for starters. It wont drop out of 4th until 25, which makes the motor bog badly around 30 trying to accelerate back up without flooring it. Under harder acceleration it shifts at strange points, usually earlier than it should. Checked the fluid and it looks / smells fine, and is at proper operating temp level. Checked all the connections on the trans itself and didn't notice anything loose or unplugged. Any ideas? TC going out? Its just strange it was more or less an overnight thing. Thanks!

[Bentley1110]

Dr. Evil I'm no tranny expert by any means but I would take it in and have them scan it and tell them to focus on the solenoid pack in the trans. I'm having the same problem and i just replaced mine. Hope this helps.

[Dr.Evil]

Thanks for the input! I will get it scanned and see what comes up. Hopefully it isn't too involved to repair.

[Bentley1110]

If that is what it is, it's not too bad. You have to drain and drop the tranny pan. The solenoid pack is at the back passanger side of the pan area. There are, I think 6 to 8 torx screws (#27) and 2 - 10mm nuts. There is a wire harness that connects thru on top that needs to come loose as well. Take the old one out, there is an o-ring on the solenoid that you will need to re-use if the new one does not come with it. Install the new one and the torque specs are 100 in. lb. Bolt the pan back on and fill the tranny back up, somewhere between 8 and 12 quarts, at least that is what i lost during the process. The worst thing about this is that you will probably find out what transmission fluid tastes like...lol. Hope this helps. P.S. on a scale of 1 to 10, I would say about 4 as far as dificulty