...ignition coil, ignition module? ? ? Both located on the front of the drivers side head...and don't use MSD coils on these cars, they're crap...JMO.
Sometime these parts get heatsoaked and will give you grief starting.
Did you use an aftermarket Opti as a replacement? Some on this board will tell you about the Opti fun I've had...replaced 3 Opti's with crappy A/Market units before going back to a GM Delco...Summit racing will deliver to your door for about $450.
Also, if you have your old Opti, open it up and see if it's corroded or full of oil...if it's corroded out, check your Opti vent tubes for cracks and make sure the air check vavles are working proper. There is a blue disc like filter in the tube "near the ign. mod/coil" remove it and hold it up toward a bright light and see if a tiny pinhole amount of light gets through, if not you will need to use an "extremely small" pin to clear out the obstruction in the filter or replace your vent tube assy. Remember to replace valves and filters in the right flow direction.
-Check your water pump for signs of leaking out the weep hole..."Big time Opti killer" I put an electric water pump on and bye bye leaky pumps.
-If your Opti is full of oil, you will probably have a leaking seal on the timing cover from either the water pump or the Opti seal itself...they are dry press in seals and can be replaced fairly easy except you'll have to remove your Opti again?!?!
Look for an oil drip on the metal pipe from the "AIR" system that sweeps just under the bottom of the timing cover
-When your new Opti was installed was there new coolant spilled ?
-Have you washed your engine bay with a hose? Another big no-no with the LT1...will saturate the Opti
-Don't spray things like WD-40 onto your opti to protect it from moisture.
-Check your Opti harness connector for signs of green corrosion on the pins and make sure the rubber seal is in place on the connector...difficult check with the water pump in the way...If your harness needs replacement, check "EFI Connections" for a new part.