My wifes car('02 4AT) has a strange problem that I could use some insight on. When the gear selector is in D there is zero problem...for now.

Issue 1: When the gear selector is in 2nd, the transmission will slip with 50% throttle or more. Revs go up, it feels like you hit some ice and it makes a vibration and buzzing sound. Car returns to normal when you let off the throttle.

Issue 2. When the gear selector is in 2nd or 3rd and you let off the throttle completely, RPMs drop to around 1K until you reapply throttle. This is very noticeable when downshifting from D to 3rd or 3rd to 2nd.

All I have done so far is replacing the trans fluid with no results. I am leaning towards a new solenoid pack but would appreciate another opinion. Again, there are no issues when left in D.

 

The car isn't throwing any codes either. Im thinking if it were mechanical the problems would exist when in D. TCU? Im gonna research and think a little more before I buy a new solenoid pack.