Catalitic converter

dude seriously where did you get the idea that the cat would cause these problems??? thats like blaming your air filter for making your tires wear out too fast  
solid axle chevys cant be beat
78 K5: 350 V8,700r4,np208, 8 lug D44 4:88, 14 bolt 10.5 4:88 with detroit locker and 35 inc parenelli jones dirt grip tires

to much back pressure... my old truck completly died because it was plugged so bad. i got it running again and it blew everything out when it finally fired  

But if it was a plugged CAT, it would not come and go. You have other issues, not CAT.  

i had a dodge doing that, turns out it was the EGR valve stuck and it would die at the light and to keep yuor foot in it to keep it running.