84 NA. My first Z ...bought it not running...I'll admit I'm in a little over my head but I don't regret it yet.

New CAS... fuel pump ran to battery and with a little starting fluid she'll start and run and even restart pretty easily. Just won't cold start at all without that first squirt of fluid.

So I found this....this the harness for the CHTS correct? End was disconnected and tucked behind the distributor cap. My question is....do these just come undone? What possible scenario would this come undone and make its way up from the timing cover?
Could it be easily yanked up on accident or more likely someone forgot or didn't know to reconnect it after a repair?

No, they don't normally just come undone. A detached chts will make the ecu thing the car is always cold, meaning hard restarts when warm, should have no effect on cost starts. the problem is once warm it will run rich to the point of fuel fouling. Difficult cold start without the starting fluid could be the fuel pump and or the fpr.