My 97 Z28 has a small misfire issue.It showed P300 code(multi-misfire)so I cahanged plugs,wires and fuel filter.Still messed up?It runs strong when I floor it but hesitates if I use cruise control or take off slow.Is it an optispark issue or what?Do I need to change the distributor cap?Help,help,help...

Have you checked fuel pressure? Have you cleaned out the throttle body with choke cleaner or such? Need to also check to see if any of the injectors are not firing... Optispark is real sensitive to water. Drive thru water in the last month? Know you got a bunch rain recently.