I think the flex plate cracked, I also had a gm mechanic come out and look at the car and he also thinks the same. I have a clanking noise at idle but goes away, or get quiet with revs, and it is not very consistant either. I took the inspection plate off and the torque converter bolts are tight. I was turning the engine by hand and every time i get to a certain spot it will make that clank noise. I checked the oil, looks good, no metal from the bearings. So, the engine has got to come out to change the flex plate and i do not know if i should just replace the flex plate or go all out. I would just go all out but this is my DD and I can not get another car every day for work and I dont really want to spend more money on the car. Every month the car ***es up, first the fuel pump then the trans, now this. To go all out i was going to pull the engine, get a L36 morad engine, XP cam it, send the heads out to get inspected and worked over, swap my top end over, porter blower, 75mm t/b, send the headers out to get coated. Right, like thats ever going to happed, lol. I talked to some people and they were saying that the flex didnt crack from power but harmonic balancer. I also need to upgrade to the H-body or the 04+ style. At idle i watched the crank pulley and it was moving a lot, do not know if that is normal or not, probably not.