I recently bought my 1999 Z28, auto with 86,000 miles. I have driven it about 2500 miles with no problem.
Today I take off from the house and as it shifts from 1st to 2nd it seems to slip? Drove on a ways and manually shifted the same way and no slip. Did this to me again under mid acceleration.
Long story short the tranny will not slip if shifted manually and feels as though it does slip in drive every +/- 15 shifts?
I am guessing where this headed but wanted some of your opinions.
Fluid is full and clean. Thanks guys

 

First to second is normally a pretty fast shift. You said fluid is clean and full but I'd jump through all the hoops and check/doublecheck the level a couple times - mine shifted weird when it was just a little low - never threw a code either.