1977 F-150 Ignition module/no start
New to the forum so forgive me if im not posting right. Anyways I got a 77 ford with a 460, Mallory Hei ignition and fairly stock everything else. I was out of the country for about 9 months and I had my truck sitting, ran fine before this. Well when I come back I service it all up, change the fluids, and a little sea foam for the carb and tank. Well after about a month it starts dying out of nowhere. I start it back up and it will run a little further. So I figure I am having either coil or ignition module problems. I replace both with the kit from Mallory but it came with a different type of module it's a hyfire hei module part# 699. Truck only cracks after I do this so I remove the module since it looks different than the original and put the old one back on. It start fine but dies without rhyme or reason while driving. Doesn't matter speed or rpm. Sorry for being long winded. Any help will be great!