I have been reading many different threads here and just signed up to get some specific help. I have a 2004 LS that was shifting very hard from P to R or D and also shifted hard while driving. I changed out the solenoid module and it seemed to get worse. I drove it hoping it would get better and it did not. It started 'screeching' when shifting I then sent off the PCM and got it repaired,put it back in and now it seems to be better but doesn't shift in to third and is very erratic. I am at my wits end. But I did see where someone said it could be the COPs and plugs. I am concerned that I may have done things in the wrong order and could have damaged the tranny and or pcm since i didn't change out the COPs prior to putting the PCM in and trying it.