2000 Impala 3.8L 4T65E-HD
When slowing down to stop (red light, stop sign, etc.) I don't hear or feel any abnormalities. When I take off, the trans will begin in 2nd gear immediately kick into 1st gear (I feel a strong kick) and then shift normally to 2nd, 3rd, 4th, etc.
Please note that this problem happens more often when the transmission is warm (i.e. hot summer day or extensive driving).
I know this is a trans issue because if I manually shift it (1,2,3,4) the trans shifts fine. This has been going on for a couple years when I received the car. The fluid is clean. No check engine lights.
Anyone heard of something like this? Could this have anything to do with "OEM boost sleeve assembly wearing"?