Solenoids can work sluggish during cold fluid temperature and perform better when it warms up so it is not surprising to have the transmissuion working well only after warming up.
Abnormal cold trans fluid temperature erratic operations can also be due to fluid line pressure loss cause by worn/aged clutch sealing rings.
Incorrect speed sensor readings can cause harsh or erratic readings but at speedometers might not show accurate readings at very low speeds. Is your vehicle equipped with cable driven or electrical controlled vehicle speed sensor?
One thing you can try, check engine to body ground circuit connections, ensure they are clean and tight. When ground circuit connections deteriorates in capacity, they can cause abnormalities with engine and/or erratic transmission operations.
Harsh shifting and slipping are mostly due to faults with the valve body/solenoids but you cannot rule out pressure leakages.
If the harsh shifting has a temporarily pause as if there is temporary loss of contact before gears engaging, it could be due to pressure loss, meaning a fault with the trans and requires a rebuild.
Wednesday, January 18th, 2012 AT 8:32 PM