even with the sec arse valves pulled it shouldn't do that , its running lean at idle ,, has it been mapped ? plugs OK? a very hot tip plug can cause it to fire prematurely ( wide open for sex joke ) right exhaust cam clearance?? does the exhaust get white hot ?? its all the signs of running lean or suckin air where she shouldn't, as a lucky man once said she can suck a golf ball through a lenght of garden hose, try spraying wd40 or carb cleaner around where the bodys mount to heads and if it stalls then you've a leak ??