Usually servicing a transmission after its not working right makes it worse. I would start looking into a 4l80e with the HD2 kit if you plan on upgrading power later on. I rebuilt my transmission in my shop class when my 3-4 clutch pack went and beefed everything up. I only had 65,000 miles. The weak point on the 60e's is the whole transmission basically. 4l80 is the way to go.