1999 GTP transmission hard and eratic shifts got TCC solenoid code replaced the torque converter solenoid still same problem also the tach will move upand down while driving when engine speed unchange?
I had a similar problem with my 2001 gtp. I had to replace the mass air flow meter. This got rid of the tach problem and weird idiling. I still have a hard shift only in 1st gear now! That problem I'm still trying to figure it out. Hope this sheds some light to your problem!