Had car warming up in the garage a bit before heading out for a drive. Just dies, fires up again, runs for a while but dies again.

Now it wont start, last time this happened I had a bad ECU. So I always keep spares, but I tried one known working ECU and another new one I bought at NAPA.

Anyway, I have fuel to the engine, and I checked for spark out of the coil to the dizzy cap, spark present. Checked for spark at the #1 plug, have a spark but seems a bit weak. My coil is new in june, a blaster high vibration one, I got 12v at the + coil terminal with key on, 4-6v on the negative. I checked the pigtail coming out of the distributor has approx 350 ohms. Rotor is turning inside dizzy, I tried 2 different ballast resistors. At one point I flooded the car, so I removed all the spark plugs to vent the cylinders and clean the plugs off, Removed bulkhead connectors and visually inspected ok.
I am unsure where to check next..........any suggestions?

make sure that your battery is fully charged and that the charging system is working properly. Ignition needs at least 12 volts on a Mopar ignition system to fire.

You might pull the idle mixture screws and shoot a 2 second blast of brake kleen into each port then replace the screws. I'm assuming your idle speed/idle mixture/initial are OK

Thanks for the suggestions guys. Turns out the coil was at fault. Primary resistance checked out ok at around 1.0ohm, secondary measured around 67kohms.

The new one measures 1.0 ohm and about 51k ohms out of the box.

Msd blaster high vibration coil. Only had it installed since June!

Success! & I was considering a high vibration coil for the stock car. I did have a MSD 6 that died from just sitting on the bench. I never forgot the one guys' moniker (on here): Might Sputter & Die

I'd still call MSD and see what they have to say...Two months seems a little short for the coil mabe you could get something out of them...But don't hold your breath...Mabe the boat coming from overseas was a little rough on that trip..

first thing they (likely) will ask you is how much ballast you used

Ok are you ready for the sequel?

Pre-cursor......I am indeed using the 1.0ohm msd ballast resistor,

Just finished a 475 mile road trip today, no problems the car ran fine.

I am experiencing issues with my elect fan, i have a simple fan controller ( derale) running one fan. I have 3000 miles on the car and last week the fan started cycling on and off rapidly then just staying on. It has a setting adjustment and I tried playing with that but it didn't help. So I just unplug it for the long drive on the hiway, and if I was in stop and go traffic I would just reinstalled the fuse. I originally thought it was a fan relay but I think it's the control module or the temp probe.
Anyway.....
Both failures ( when the car dies) have been during long extended times of idiling, what's goin on? I am trying to get another coil now, I am scratching my head .......drove all this way to make a cruise night in my home town

Well back on the road after replacing another coil. This time i got a basic accel coil. Car started right up. I don't know what's killing the coils, I have the block grounded on the drivers side head to the rad support thru the negative battery cable, passenger side head bonding strap going to the ecu and the firewall. Maybe not a grounding issue....?

i had a problem with my truck dying after it got some run time, turns out it was the coil. it also showed itself as intermittent no start even when cold a few times as well.
turns out one coil was an msd blaster, very few miles. replaced with an old accel superstock and it ran fine for a few longer around town trips.

then after reading i decided to jump the ballast on the coil side so it had about .5ohms. accel told me the coil was internally resisted so it needed no ballast.

after the first long drive it started dying on me after about 25 mins. if i let it cool down for about 10-15mins i could get it going for another 5 or so.

i replaced the coil with a new accel and then just put an msd streetfire on the thing. no problems since...

Heat might be doing it, where is the coil mounted? Where is the fan controller mounted?

Years ago, I help a friend put a 327 into his Chevy Luv and we had to run an electric fan. Found out the hard way that the Vette temp sensor we used to control the fan needed to control a relay and not the fan directly, killed the sensor. Is the controller cycling a relay to turn the fan on and off?

Coil is mounted on the back of the intake right beside the dist and oil press sender. Considered the heat thing myself...but that's the stock location for many cars so it shouldn't be cooking the coils just all of a sudden. Maybe the quality of parts from china are truly that inferior,

The fan relay and control module are mounted right beside the rad supportmount kind of under the battery tray, definetly not the coolest location, maybe heat is too intense for those Chinese electronics

Yes it is poor quality in general & Murphys law EDIT get another one and one for the glove box & make sure you have enough ballast (or even go up a bit there). as you know breakdowns ain't no fun & ususually happen at the most inopportune time