This is starting to sound like a PCS issue.
http://www.tripleedgeperformance.com...ift-P1811.html
So I have 206k on my engine and trans. I started getting hard shifts all the time around 145k and the only remedy was turning off the engine, waiting for a few seconds and then turning it back on. If this is the case for you then a shift kit could help.
http://www.grandprixforums.net/threa...ailed-Pictures
I personally did a shift kit and a trans cooler just to see how many more miles I could go without a rebuild.
No I get a delayed engagement on occasion, but this happens only when I'm at a dead stop and go to hit the gas I get a delayed or bump stop some people say. This does not happen every time or with every shift though, only on occasion. Maybe once a week if that, but at least 2-3 times a month I guess. There is a lot of information available.
http://ls1tech.com/forums/ls4-perfor...ement-fix.html
http://www.grandprixforums.net/threa...e-or-Shift-Kit
http://www.grandprixforums.net/threa...D-Transmission
If it were me, try the shift kit. You can get them for less than $50 nowadays and they are easy to install. If you can't afford something new or the rebuild, this might be your best option to keep it running for as long as you can.