Welcome to the Forums
I am Shane , your Lunatic Captain and Ill be flying past Eridani station in about an hour, please fasten your seatbelts as the Pirates are hungry this time of year
I actually , and I am very proud to say , I have won the game with the Freighter. I understand how frustrating it can become and many times I jumped for joy at the sight of the Corporate Cruiser racing in to save the day ( and usually saved me by dealing with the mean ships that had no consideration for my love of survival ).
the IM90 ( and there are other Ion weapons close to it ) is usually found in Ringer and Taikon stations, it costs about 150 thousand Rin, I have not got one in awhile so I do forget : I spend alot of time mining , some games I play are just to go mining and relax with no thoughts to trying to win the game, which can take up to 16 hours or more the way I have played it.
I found my first IM90 for sale and when I mined up enough ore that I traded to the Ringers for Rins I got one but I also have tried Ares weapons salvaged from wrecks and other Ion weapons as well.
I once sat on the Heretic star shooting the Iocrym with a Tev9 because I thought I lost the game : the Forums gave me the information about the extra ROMs being inside the Iocrym wrecks that I needed ( as RPC mentioned above for you).
Pteravores are one of the funniest things in the game : I remember the first time I met them, I destroyed the nest then DOCKED with it: stupid move.

I have learned to shoot them with anything then coast in to draw them out then lead them away until they die (until the nest is empty ) it canbe dangerous but with time you get better. if you refuel just as you are about to die you can usually survive : or in some cases the manipulators can shoot them off you but that is dangerous too.
what I would suggest for your current game : back track. go back to the other systems to take on Ares and other hostiles : trade, mine and have fun while you shop and gain credits and Rins to buy bigger weapons and shields. you might even try drawing hostiles to friendly stations and then loot the station if it gets destroyed before the Cruiser shows up ( not always a good idea but sometimes it works )
Flying Irresponsibly In Eridani......
I don't like to kill pirates in cold blood ..I do it.. but I don't like it..