My problem started out with the normal od lock and unlock issues. I cleaned all the grounds and tightened them and did the same with the battery terminal connections. That seemed to solve the problem for about a week and a half then it started again. I ended up replacing the APPS and that worked for all of three days. Recently I have replaced the alternator along with the brake light switch. Now when I drive it if I barely accelerate the rpms will shoot way up to 2500 or so. It will shift normal when doing this however it will usually start the od lock and unlock a few minutes later. it will lock and unlock several times before downshifting a gear and sometimes staying in third. sometimes it will downshift without warning going 75 mph down the highway. I have tested the new alternator to make sure it was good and not sending to much AC current and it checked out fine. I am at a bit of a loss on this one. Any help would be great. 

Do you know if the ECM was updated with the latest software? I have the 99 Sport model and I had the software update done at the dealer and they put a sticker on the crossmember by the radiator. I'm not sure if this will help you but it did help me with mine. If you need I can post a pic of the sticker with the info on it.

I know which one you are talking about. It looks as though that it has two different things done

I have tested the new alternator to make sure it was good and not sending to much AC current and it checked out fine.

 

Could you please post your AC voltage. A lot of people assume a much higher number than what it should be.

 

Normal: 0.01 to 0.05 VAC

 

Failure: > 0.1 VAC

That sounds just like the time my speed sensor on the side of the transmission failed. It would decide to downshift whenever it wanted. It is a five minute fix. Just unscrew the old one and screw the new one in then plug it in!

I thought about that since they are easy and pretty cheap as far as I know.

Throwing this out there I had the Overdrive and T/C lock up solenoids go out on me lest week and it was causing a bad hunt in and out of 3/lock up overdrive and lock but at the same time I was fighting 2 bad injectors

Mine hasn't happened for the last two days which is odd because I haven't done anything. Was yours constant or sporadic

I put in a speed sensor and now everything seems ok. RPM's are normal and no weird shifting