'84 volvo stalls unpredictably
 

does anyone have suggestions?

It can go for days without stalling.

It will rev up at a stop light on its own, so I need to put my foot on the break harder to prevent taking off.

Sometimes while shifting gears, mostly to reverse.

Car smells like gas when windows are rolled down.

other people say there's an air leak by listening, but I can't hear it. I sprayed starter fluid on the hoses to see if the rpms would go up but nothing happened.

if it is raving itself up then yes there is an air leak
if you smell fuel its possibly trying to compensate by enriching the AF mix

check the air tube going to the intake (the corrugated one) as those are prone to cracks along the ribs
also check the IAC (idle air valve) since you said it revs at idle that valve may be allowing too much air in, or have a leak itself

thanks Nichals :) I'll check it over. There was also a loose bolt that holds the fuel rail down, that could probably do it too and cause gas to leak out.