Hey any help would be appreciated. I have a '99 R/T 5.9 Automatic with 90k miles and the transmission all of a sudden stuffed up today. It holds 1st gear till 3800-4200 RPMS before it shifts out. But then from 2nd->3rd->Overdrive it shifts normally.
Now a bit of background. About 2 years ago I panic stopped and the sloshing of fluid picked up sediment and covered the RPM pick on the tailshaft of the tranni. So I changed the fluid/filter and pulled the sensor out wiped off the filings and it shifted normally again. So I've already cleaned the sensor off and checked the fluid level and all are ok. I also just unhooked the sensor and it did the same thing. 1st 4500 then shift to 2nd.
I'm guessing it's in the valve body, but I'm not positive as I don't know the composition if certain channels can be clogged or if everything is electronic. If there's anyone that has had the same problem help a brotha out!

 

On that trans, it's all electronic. Have you replaced the speed sensor?