slamming gears

We have a 1999 Silverado. Vortec 5.3Litre. The tranny is a 4L60E auto tranny. When we drive it for awhile the truck shifts harder and harder when it is shifting from 1st gear to 2nd gear. What could cause that. It never does it shifting into any other gear. We were told it was the torque converter. Any suggestions on what we should do???

its a programming hiccup.....disconnect your neg battery cable, press the brakes to drain all the power, wait fifteen minutes and hook it all back up, if problem persists, start lookin at a rebuild or new PCM, one or the other

run it till it dies...shifting hard will actually help the clutch disks last longer cause they dont have a chance to slip. your getting the same effect that a hypertech stiff shift adjustment makes for free.

had a 93 that did the same thing. started when i had about 100,000klm's on it. the truck has 400,000 klm's on it know and is still going