There isn't a way to do an AC simulation without frequency sweep. This is necessary if, for example, I want to plot the output of a circuit with a fixed AC source when I vary a resistor (if I use an AC sim and a param sweep, then the plot will consist on many points/lines, one for each resistor value, with X representing frequency, instead of a single trace with X representing the resistor value).
Possible solutions are:
* AC "constant" simulations don't sweep frequency.
* Allow to select which parameter goes on which plot axis.
* Add a "RMS simulation" (this would work even for circuits with different frequencies).