I have a 1973 nova with a 406. I have noticed an intermediate vibration at 2000 rpm and up. I have been having trouble to get it to idle in gear, and the only way it will barely idle is to have the timing set at 22 degrees advance. I was wondering if this much advance would cause the vibration. was also wondering if the trans converter would cause this, have a vega 2800 stall. Is this possible, unhook the converter from flywheel and start engine to see if vibration disappears. Any help would be appreciated..