Karsten Sellers

Ok so I need some help and haven't found a lot of information on this. I have a1999 v6 Camaro with an automatic transmission. I just bought it and it ran perfectly for the 80 miles it took to get it home. That evening I turn the car on and it starts knocking a bit I revved the engine and it died. Then it would not turn over. The starter was completely fried so now it has anew starter and new battery. It will now turn on but there is still a knocking and obnoxious screaching sound. It sounds like it is coming from the transmission and starter area. The it could possibly be the flex plate bolts but I'm not sure. Also it will occasionally stall in neutral but it always stalls when put in reverse.