My LT1 sometimes has a hard start condition. Only when it has sat for a while like overnight and all day at work. It is throwing no codes or anything. My optispark has been replaced 35,000 miles ago. If it were the ignition module it looks like it would do it when warm or hot. Fuel pressure is also good. Thanks

 

check your fuel pump relay. the fuel pump is tied into both the fuel pump relay and the fuel pressure switch. if your relay is bad the engine will still start when you crank it because it builds oil pressure and closes the switch, but it takes more cranking to get it to build enough pressure to start the fuel pump. just an idea.

EDIT:

Just re-read your post and you said you have good fuel pressure. probably safe to say the fuel pump relay is ok and problem is something else. sorry about that.

 

Update: At idle in open loop the engine surges. I'm beginning to think I have a terrible vacuum leak. When warm the engine doesn't surge and acts normal. The intake gaskets were replaced not long ago and I have replaced some of the little rubber elbows that were dry rotted. I sprayed ether around the intake and the vacuum ports and have come up with nothing. Why would this happen when engine is cool only? Oh, the egr valve has also been replaced.