93 4l60e Delayed engagement and no lockup

[jdla140]

I recently acquired a 93 K1500 with a 6.2 diesel and 4l60e. When cold, there is a SES light and first gear will "disengage" at a stop and re-engage when you roll forward or hit the throttle slightly. TCC will not lockup, and it seems to hold gears a little longer than it should and shift pretty hard, when it warms up the SES light turns off, first gear works fine, it still shifts a little hard and locks up anywhere between 35-45 miles an hour. Trans has about 40K on it, fluid is right on the level and not burnt. I've seen threads that say the ESS is at fault, there is even a TSB, but it only specifies the issue with the 4l80e. I have confirmed that my truck DOES have an engine speed sensor, could this be causing the problem? a 4l60e was only available behind a mechanical 6.2 for 1 year, so information is hard to come by.