ok heres the scoop on my 00 zts, when i first accelerate and the tranny shifts from 1st to 2nd it does so rather harshly and sometimes it slips going into 2nd and the eng. revs some and then engages and when it doesnt slip and the t/c locksup in 2nd it does it harshly,the weird thing is it seems to be smooth going from 2nd to third,however,when i slow down and it shifts down from 2nd to 1st its harsh just like the upshift, is this a sign of a torque converter going bad or is it something else all together? also,would this throw up a check engine light?