Ok so my 99 gtp runs and drives great then all of a sudden the trans quits. But if i turn the car off for 30 seconds the trans kicks back in and goes just fine? till i stop then i have to restart the car again anyone ever heard of this issue? I have no slipping at all in the trans. Also if I switch it to natural while moving my speedo drops down to 0mph when I know I'm doing about 30

 

Dont know about the Speedo but when the solenoids are having problems they behave in this waym try taking it to a trans shop and getting the codes scanned.

 

Mine was doing this but only for 3rd gear. Once the trans is at normal operating temp, it would stay in second gear. With no CEL. I had to shut the car off and sit for a minute. Then it would work fine.
The harness to my PMC was wired wrong causing all types of funky things. So I went in and wired it according to the service manual. That's when I got the P0720, I think it is, TCC not working or stuck open. The TCC controls Torque Converter lockup. And now I have 1st, 2nd, and 4th gears. I have to exculpate up to 44 MPH then release the accelerator to get it to shift to forth. It does shift from 1st to Second. But the RPMs are 300 to 600 higher than I would expect.

I think like Dave, that you have at least 1 bad solenoid in your trans. I too recommend you take it to a Trans shop, not a auto shop that also does transmissions.

 

Alright so i changed my fluid and filter and it was doing great. Tonight i went to pick up my son and the car started with a Tcc (Torque converter clutch) code. I'm pretty sure that's the Tcc sensor? Hopefully... I really don't wanna change the torque converter.

 

Come to think of it, I didn't got the TCC code until after I changed by fluid and filter. I really wish I had a garage to work in!