I am experiencing intermittent hard shifting. This happens periodically. Otherwise the transmission works perfectly.
This was my the cause of my problem on my 93 C1500 with a 4L60e. I had hard, late shifts and a bit of idle fluctuations. Fuel pressure was marginal @ 10psi. Replaced fuel pump and got 13psi and hard shifts went away.. smooth again. I assume because I had to use more throttle than normal for given speed/condition the PCM thought I was trying to accelerate hard when I really wasn’t.Check your fuel pressure as well. The TPS tells the computer when to shift based on speed and throttle position