Shifting / Speedometer problem

I have a 99 Express Van with 4L60E Transmission. A rebuilt trans was installed about 200 miles ago and was purchased from Autozone. The removal and installation went fine. Had problem with early shift and eratic speedometer reading right after install. Replaced the VSS and thought we fixed it with the help of the good people on this message board, but the problem is back just not as bad. The 1st round the Speedo would read 60 when I was actually doing about 30 and shifted all gears way to soon. The VSS was replaced with an aftermarket sensor and worked a while as well as settled down eratic speedo. Then the trans started shifting early again from 2nd to 3rd and back to 2nd all the while I notice the Speedometer was also jumping up and back in correlation with the shifting (around 10 - 15 MPH). Of coarse if you take off fairly fast, you just get the early shift from 2nd to 3rd (not bad but just not right). So I purchased another VSS (3rd one) and it seems to have helped some, but still shifts too early 2nd to 3rd. I read on another post that someone had trouble with aftermarket VSS and suggested getting an OEM. Could this be the issue? Has anyone else heard of this? I am at a loss and I guess it will have to go to the shop next week. Please help. Oh, I should add, there are no error codes.

Yes, avoid aftermarket VSS and run ONLY the OEM part. Especially if your aftermarket VSS came from Autozone.