Code 34 EGR voltage above closed limit - Failed sensor, carbon between EGR pintle valve and seat holding the valve off its seat. Remove the EGR valve and clean it with carbon remover. Prior to re-installing see if you can blow air through the flange side of the EGR by mouth. If it leaks, there is carbon stuck on the pintle valve seat, replace the EGR valve ($85-$95).
This will affect idle quality by diluting the intake air charge
Code 67 - clutch not depressed (5 speed) or car not in neutral or park (auto) or the A/C was on when you ran the test (it is supposed to be off). Possible neutral safety switch or wiring problem. You can generally ignore this code, since it has no effect on engine performance. The code will affect some of the engine running diagnostic tests the computer can do if requested.