How easy is it to foul plugs?I just got my new motor running with an old carb and it is running rough.The plugs are jet black (not from oil).It doesnt want to idle no mater where the timing is at or the idle mixture.Around 1000rpm it starts to stall out.It will not idle lower than 1000 and when I put it in gear it tries to die.It deffinatly has a miss to it.I have tried different carbs but they are all about the same.I ran the cranking compression and they are all close to 175-180 but it hasnt really been broking in good yet.The plug wires are ones I allready had but I thought they were good.But I have some new ones on order,everything else is new,cap,rotor,plugs,spring advance kit with the middle springs installed (HEI).They vacuum at 1500rpm is about 12 or lower and it jumps around some,I think because of the miss but I'm not sure.If i rev it up to 2500 or higher I can feel it shaking and missing some.It levels out and runs alittle smother after a second or two but still misses.I have reran the valve lash and sprayed carb cleaner at the base of carb and intake but I cant find any vacuum leaks but thats what it acts like is a vacuum leak. I AM STUMPED. ANY HELP?