Rough Idle

I have a 90 Seville with the 4.5l. The car has 195k on it, but the engine still runs very good and strong. The problem is a rough idle and a slight smell of fuel when idleing. The motor makes no noise and has not burnt a drop of oil (almost 2000 miles on this oil change) so I think it's worth doing some work to. I have read the TSB on the injectors for this car and having to run premium (noted in several TSB actually) my question is about testing the injectors. The resistance on the injector is supposed to be between 14 -18 ohms, is this the only way to check them, other than the injector tester they list? The reason I ask is they note in the TSB about testing the ohms not being accurate enough to determine the injector good or bad. So what do you do? Every place I call hears "Cadillac" and the price goes up.