Join Date: Mar 2002
Location: Austin, TX, USA
Plug the PCV line and see if that helps. The PCV valve is essentially a flow regulator. It could be that it is flowing too well and acting like a vacuum leak. A different PCV valve may fix the problem. But disconnecting it should tell you something. If it don't change, it probably isn't it. Also make sure your mechanical and vacuum advance are working properly. If the mechanical advance is kicking in too soon or the vacuum advance can is too tight, RPM changes will cause timing changes.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI