So today I went to leave school and noticed my Z would shudder at low RPM. I worked on it earlier at school but was only using the scope on my wheel speed sensors and injectors so I didnt mess anthing up there. I can feel it in the steering wheel, shifter and floor between 1500-2000 RPM. Nothing at idle or above 2000. It does it with the clutch in, out, in gear, neutral, or driving. Pretty much whenever so I ruled out from the clutch back. Its not horrible but its noticable. Fuel pressure is fine. I didn't see anything arching under the hood.

Another thing - A few weeks ago my vacuum was about 18-19" at idle. I did some ignition work... New coil, ICM, 6AL, and the car ran better but my vacuum dropped to 14-15" at idle. Probably a coincidence but I dont know. I think maybe before the ignition stuff it idled a little high from running rich and that raised the vacuum. Now with the new stuff it idles where it should and with my cam it shows were the vacuum should be (14-15"). My brakes work fine with the low vacuum but I was wondering if there are any other downfalls to low vacuum. My teacher was saying something about to much crankcase pressure because the PCV wont work right but that doesn't seem like an issue to me. Any info would help. Thanks

Nathan