911sc running problems?
 

Car is a 1978sc with 964 cams headers into dual in single out muffler. This car dosn't like to run at low rpms when driving car after warmed up it likes to have the revs above three thousand or it complains. It seems to bounce back and forth through the drivetrain. When driven spritedly it drives fantastic it is only when driven in traffic with the rpms low that it complains. Maybe a 911 cannot be driven like a normal car with low revs. Do I always have to keep the rpms up or is it possible to drive car like a normal car in traffic?

These cars do like to rev, but they should still be pretty steady @ low revs. My car has mods similar to yours, and when this happened to me I found my mixture was slightly rich. This can also be a sign of a too lean condition however, so you have to be careful. A bad WUR or air leaks can also be @ fault.

I would try the mixture first. Do not turn the screw more than 1/32 turn @ a time, and drive it and see what happens.

The mixture is set at the 3.5% setting so I don't think this is it.

Wondering if the mixture setting would change with the cams and muffler change. Also car has no emissions on it and no cats. she runs great when warmed up and driven aggressively just alittle weird when not driven hard. I will try the mixture if some one else cannot give me any more advise on this problem.

Check for vacuum leaks especially at the distributor advance and make sure the advance mechanism is working properly.