4L60E constant shifting between 3rd and 4th

[yukonrrican]

Hi to all:
I have a 1997 Yukon GT 4wd with 124K miles. It has 3.46 diff with 33in tires. This weekend driving in the highway it start to shift constantly between 3rd and 4th shift between 50 to 60 MPH. This morning driving to my job, it don't do it at all.

Any advice will be appreciated.

 

[pontiacgta2002]

Same issue i had. I installed transgo 4l60e shift kit. I think you can also get just the iso conversion valve. Fixed my issue, no more ossilation issue in 4th or 3rd gear from the torque converter engaging and disengaging.