ignition problem/high idle
 

I need some help. 1981 SC. Car ran nice and strong.Started well when cold, normal warm up, everything as it should be.Once the car was at normal running temperatures and I stopped and shut off the ignition and the car was restarted within minutes or a few hours later the car would start fine but the engine would want to die and then start running normally and then start to die again and so on, while this was going on the tach needle would fluctuate wildly and some times stick in one place and then starts moving all over the place again. I thought the problem was the permatune box? So I replaced it with a MSD unit and also installed a tach module,new msd coil and plugs. The car started immediatlely started up, the exhaust note nice and smooth, however, the idle speed was up to 1900 rpm. Is this normal? MSD techies say no. They think it is a vacuum leak? I can't find one. Help please.

It is normal for the idle speed to be up around there when starting from cold. The AAR keeps it up. When the engine warms up, does the speed drop to 950?

Once the egine is warmed, did you try lowering the idle speed via the idle speed screw?

Checked vacuum hoses again, started car up, rpm 1900, let car run adjusted idle screw as much as I could. Idle now 1050 rpm. When I give it a little gas with the pedal, it develops a miss, no backfires, but exhaust note is breaking up and does not rev up smoothly. Plugs? Wires? Or both? Plugs gapped at .050, new rotor, new cap. Thanks for the response.