1983 Thunderbird ignition problem

I have an 83, V8 5.0 Thunderbird with 140,000 miles.
If I have my car sitting around for 1-3 hours and try and start it, occasionally it will not start.
However when it starts, in park the engine will run fine for around 5 minutes then will start to repeatedly choke, run, and eventually will die unless I hit the gas. Now if I try and drive the car I can back up fine yet as soon as I shift to drive and hit the gas the engine will shutter or will die if I press the gas too much but if I barely press the gas I can drive fine.
When testing for a spark I turn the key and get a brief spark. The spark then disappears as I continue to crank the engine. I've adjusted the spark gap at various settings but there is no change in the spark.
This problem has started to happen more often lately. In the past when my car would die out during driving I could jump out the car and would get full spark when cranking the engine and engine would start right up with no hesitation.
I've had the ignition coil, ignition modulator, and distributor cap replaced. It is not in need of a tune up; I have checked the spark plugs and plug wires. I have also checked the wiring from the ignition coil to the ign. modulator to see if ripped etc., there was some fraying on some wires so I repaired as required.
If anyone has some ideas on this I'd appreciate any information. Also I have all maintenance records from 140,000 miles to 80,000.
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does that car have a tach?
watch the tach while you are cranking the car.
note when you turn ign on it twitches once.. as you crank, it should bounce slightly.
If it doesnt bounce during crank, but it does when you key-on, then you're not getting distributor signal... assuming the ign module is good.
just buy a new pickup for your dist. or you might pick up a used dist and swap pickups
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No I do not have a Tach. I will go ahead and replace the pick-up tomorrow. It is worth a try. Yes the ignition module is brand new. Thank you for the information, I will post the outcome soon.
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No it does not have a tach. I am going to look into getting a new pickup tomorrow. Other than the pickup is there other possible problems?
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