Have a Holley carb? Sounds like what my old Holly used to do until I learned what a blown power valve would cause. Felt like a miss but was actually a intermittent rich condition.

I checked my compressionabout 2 weeks ago and all cylinders were 1 or 2 lbs within 150 lbs. I'll try and lean it out a little and see what happens. I might turn my screws in 1/4 turn each maybe see what happens.

what do the plugs look like, a blown power valve would be rich all the time, I believe the LS5 came with a Q-Jet, some Q-J's came with a plastic float and some came with brass ones, over the years the plastic ones will swell up and hang up in the float bowl, read the plugs first, if they look questionable just replace them, if they look good then maybe wire's, rotor, cap etc, only work on one thing at a time, check for vacuum leaks, big blocks like to shake a bit with low idle, is it a miss or shake?

Well my plugs look good...I checked them yesterday, so I increased my timing from 10 degrees to 12 and leaned my Quadrajet about 1/8 turn at a time...there now about 2 1/2 turns out and problem solved. No more missing at stop signs. Thanks everyone for the advice