OK, got the Harrison OBDScan and got the error code P0172, for Too rich Cylinder Bank 1. Original complaint, very rough (more of a shake, a clear miss)but consistent idle. Hooked up a vacuum guage, reads 19 inches and smooth, seems acceptable to me. Disconnected one injector at a time, found they all made the idle even worse, except the number one cylinder had the least adverse affect on the idle when disconnected. Reset the fault code and it has not returned in about 10 trips, but bad idle remains.

Idle smooths out above 900 RPMs. Car drives fine. Only other possibly meaningful info from OBDSCan is "Fuel Sys 1 Monitor closed loop with Fault" message, and the Short term trim is about 25% at idle, and -2 to +5% at speed. Long term is steady at about 4 to 5%. O2 sensor varying nicely between .1 and .9 volts. Replaced spark plugs, deiced the gas, ran injector cleaner through a tank (always sceptical about that) checked injector resistance all at 18.7 ohms. I can tune a Rochester Quadrajet, Holley dual pumper, even triple SU's on my old E-type to perfection, but I'm stumped on this one. Help!