Did a search and the majority deals with lower RPM hesitation, so I was wondering what are some causes for upper RPM hesitation on an LT1. Bought my '97 with 63K, it now has 121K miles on what I believe is still the original Opti. Already changed the wires with stock replacements and installed Bosch +4 plugs at 75K, otherwise everything is original. Car runs fine BUT slightly hesitates around my 55-5700 shiftpoint; nothing drastic, but you can definitely feel it. Mods are CAI, free mods, cutout, madZ28 tune. Thanks.

 

Replace the plugs. They're known to be bad, and cause such oddities for no good reason with miles on them, surprised you got that many out of them.