Stereos are pretty simple to wire in, they don't tie into much other than the fuse panel/ignition switch. So the engine & tranny swap shouldn't have effected it at all. My guess, if there is evidence of others having a problem with it, is that it is a Kenwood defect problem and has nothing to do with what you did. If it were me, I'd change the head unit out with a junk one if you have one sitting around and see if it still does it. Simple and will tell you if the problem is with the headset or somewhere in your wiring.

I purchased my Kenwood in the Spring around the time you bought yours. I have not had any issues. Sounds like it is something inside of the deck because there are only a few wires in the install so it should either work or not work, not intermittently. It should be under warranty for a 1-year or 2-years if it is an Excelon. Even if they warranty it, it will suck being without a Stereo on your commute while it is repaired.

Since this is Stump the Chump, I will venture a guess that the deck is hooked up to a non-constant power wire (like the electronic choke wire) and turns off after the Bronco is warmed up. Bad guess, but I never get to play this game :)

did ya check the muffler bearings when you did the engine swap? Those things have a tendency to go out and when they do they cause a series of other problems

Ground? Mine did that. Or did you drill through a speaker wire when you drilled for the floor shifter cable?

Sounds like an under voltage situation or if it has a wireless capability, RF interference.

Something to do with the heater. Either it was pulling power from the heater circuit or it was grounded to the heater box which was poorly grounded to the body.

A fuse?

The nut behind the wheel?

Bad ignition switch.

Did you check the stereo fluid?

Turn signal

New horn wiring.

Motor not grounded to the body or frame?

Well since you found it I guess I won't tell you to wire in a light across the two power wires and see if it goes out when this occurs. That will at least show whether it's the head unit or intermittent power. I had a 4x4 van back in the 80's and it would die sometimes out of the blue. It would usually restart after about the second try. I replaced the ignition module, check out all the ignition components, etc. it was frustrating to not know when it was going to quit. One day I had the tunes cranked up and hit I a bump. Engine died, and I noticed then that the stereo was dead also. Wiggled the ignition key and it started back up. Replaced the switch and problem went away.

Something to do with the light on the gear position indicator on the column?

Heater blowing hot air over the stereo causing overheat? (really pulling them out of the air now:)

Heater pull nob pushing on the power wire to unit?

Problem with the speaker...wrong impedance, bad/loose speaker wire connection?

Alternator

2 Batteries and it is an isolator issue?

Its a fuseable link that was on its way out and when it warmed up a little bit made a better conection than when it was cold.???????? Or a wire was broken and made contact only under perfect possition.?????

Your antanna was bad???????????????????????????????????

brake porportioning valve imbalance switch ?

Did anything else die at the same time? Lights etc?

Were you sitting on the remote?

since you said not in the cab , it would have to be something chaffed . you also said it does when you put it in drive so some where near the shift lever or brake rod . so with that said my guess is inline fuse being pulled apart then goes back together once a little road vibration is induced .

It is obviously operator error either on the install or you trying to run the damn thing and you are starting to piss me off now!

voltage regulator?

you never turned off the auto demo and it's shutting off , or your bluetooth is driving it crazy