*dies randomly, but starts right back up.

engine is a 302, carter/edelbrock carb(i believe the closest edelbrock would be a 1406), no idea bout the internals or cam, was built by previous owner. electronic ignition(I believe its the duraspark ii, anytime i browse for parts I default to an '84 ignition system).

so story time - back in august I was cruising on the highway and noticed the idle had become incredibly rough, drove (mostly) fine when on throttle. got it home, didn't have time to mess with it so it parked until this past month. one thing that stood out when i parked it was some smoke/mist coming out of the valve cover breather which i hadn't seen before.

anyways, this last month i decided to figure out wtf was going on. did an oil change, oil looked normal and black, no obvious signs of coolant. eventually after sleuthing around noticed the magnetic pickup in the dizzy was loose and making contact with the reluctor, figured that can't be good and after some brief looking around couldnt find any listing for new base plates so just replaced the entire distributor with an autozone option. fired it up, got the timing and idle mix adjusted and its idling better.

I noticed one of the idle mixture screws on the carb wasn't having any actual effect on the idle so opted to just rebuild the carb. with that done the engine is idling pretty well. pulls just above 12 Hg of vacuum(if i'm reading the gauge right), initial timing is about 16*(i'd read that in higher altitudes that going a lil higher on advance can be helpful, and i'm in denver right now).

the problem is i'm getting a pretty bad stumble when i start to rev it above 2k. you get the engine above 3k and it feels like its stumbling or misfiring, let off the gas and it settles down mostly. however even when cruising at a steady speed it feels like there might be a very minor stumble or misfire in there. the exhaust is in pretty rough shape tho with some cracks around the h-pipe so i'm never sure acoustically what's a problem w/the engine or just the messed up pipes. I just checked the mechanical advance on its own and its definitely advancing, however as it approaches maximum advance the engine does start to shake a bit.

on top of all of this occasionally when idling the engine will just die randomly, like you just shut the key off, typically after coming off load but not always. when this happens it will usually just starts right back up like nothing happened.

car as an electronic fuel pump, i can hear it when i turn the key to acc and it at least sounds normal. reading around i'd seen that the random dying can sometimes fall back to a faulty ignition switch or ignition control module, swapped those out and still having the issues. i havent done a compression test yet but that may be next on the list. I had some similar symptoms last summer when the engine was under load but in that situation the vacuum caps on the carb were badly cracked causing vacuum leaks. i did just swap in some fresh ones to no avail.

kinda stuck on what to check next. the weird thing is the stumble under load *wasnt* a problem back in august.

 

I would check for vac leaks. Where the intake meets the heads and around the base of the carb. You can use carb cleaner to help locate the leaks. at idle spray a bit around the full lenght areas I suggested, if idle rpm changes there is likley a leak at that location.