I've been having rough intermittent shifting after my car is in a lot of stop and go driving. I changed my trans fluid and filter a few months ago and it didn't solve the problem. I see that GM has a bulletin on this and it calls for replacement of the PCS solenoid. I've done a little research on this problem online and have decided to flush the tranny this time and intall a Trans Go Shift Kit first, in hopes it will cure the problem. I've read that the shift kit quickens up the shift and therefore the p1811 code does not set. If not, i'll end up doing the PCS solenoid replacement. (Mitchell 1 quotes this at $357+alignment). What's a typical cost for a 4t65e shift kit install? The Century is my beater car and i'd rather try the cheap route first and if totally necessary will replace the PCS solenoid. BTW, my car has 98k on it.