All of a sudden...fast cold start! - but why?

[Dragonslayer]

OK, what gives?

Ever since buying my '93 XJ (4.0L H.O., 2WD, auto) 3 months ago it has
always taken a concerned amount of starter spinning and praying (or cursing)
to get the beast to fire up when cold.

I've changed the CPS (new), cleaned the NSS, new O2 sensor, and cleaned
every dang connector I could lay my mitts on - including the ECM connector.
I cleaned the pintle on the Idle Air Motor - but only superficially - as I had
read to NOT pull or twist the pintle while doing this.

Although this improved things a little, it nontheless still required two (2)
quick spins of the starter (and a silent prayer) to get things going.

That is, until today.

This morning, the temp happened to be in the very warm 80's, and dry.
I hopped into the car and flicked the key - only once - the starter whirred
2-3 revolutions...and the engine immediately burst to life!

I was pleasantly astounded.

To be sure that this wasn't a fluke, I lumbered the car back into my garage
where I fiddled with the rear hatch speakers for 3 hours. The previous owner
was an absolute "pinhead" as he had severed the stock speaker wire harness,
then connected the L & R rear speakers together (using household twist-on
wire nuts) - then he hooked the speakers up to the cargo dome light. ...DOH!

After sorting this out...I hopped back into the driver's seat and, again, after
giving it one shot of the starter, the cold engine immediately roared to life as
though it were a real, "normal", car.

I'm not one to complain about hitting the Lotto...but does anybody out there
have a theory on what could have caused this fortunate change of events?

Anybody know which onboard "gizmo" is especially sensitive to ambient
air temperatures, humidity, etc.?

MAP sensor? Maybe?

Sluggish pintle on the Idle Air Motor (due to gummed fuel, internally)?