Looking for a little direction on my cold weather starting problem on my 92 Z32 N/A.

I have owned the car for 18 months and it has 54K on it and has been garage kept all it's life.
It has a few small modifications including JWT ECU upgrade, Exhaust system (cat back), KN filters, Aluminum flywheel and upgrade clutch.All these done by previous owner. I lowered it and put some period correct wheels and tires on it.

Never had an issue with the car until I moved to a new home that doesn't have a heated garage. In October when it started getting cold, the car would not start one time. After turning over, for extended period, it finally started. This has become the norm since that time. Once it does finally start, it starts with no problem there after and I can drive it for hours without missing a beat.
I went through and checked the fuel lines and tightened all clamps and replaced a leaky fuel filter. I have checked the ECU codes and it comes up 55 indicating no problems. It appears to be getting fuel (haven't measured pressure), but doesn't look like I'm getting a spark. Not sure I had plug really well grounded, so I will do this again.
Just very strange that what ever the intermittent problem is, that once it starts it will continue to run and start without an issue for the rest of the day.

Any suggestions would be much appreciated!

Put a stock tune back in it, see if that makes a difference.