There are many coins to mine with less than 4GB of ram but keep in mind their profitability is much lower than ETH and ETH already is not that profitable.

Go to
https://whattomine.com/

Put in your hashrates and see what is out there.

There are many Daggerhashimoto coins which you can still mine with 2-3GB GPUs, but keep in mind they are very unprofitable. Almost to the point where you are better off just buying an RX 470 4GB second hand since they are dirt cheap these days at $75 each.