I have a Chevy 1997 extended cab 4x4 pickup that has 115m miles on it. It has the 4 speed automatic transmission with 5.7 liter engine. The fluid was changed at 112m with no problems. Now, when it shifts from 2nd to 3rd gear, it's like a slow shift that creates a backlash in the drivetrain. All the other shifts are fine. Under harder shifting (faster acceleration) it seems to go away. It's most noticable under light acceleration. Doesn't seen to matter warm or cold.
Does the computer control the shift pattern? Can it be reprogramed?

 

Yes it is computer controlled to my knowledge and, no, reprogramming it will likely do no good.

If there has been an update to the computer, Alldata or GM would list it as a service bulletin. You can look at www.alldata.com to see if anything there in the bulletin area matches your problem. Then see your GM dealer for a full copy to see what the fix is.

If changing the fluid and filter didn't help, you might have a stuck solenoid or internal failure .