Coolant Leaking problems of the 1998 Subaru Impreza

98 Subaru Impreza 2. 5rs. I had the head gaskets replaced under warranty the first time . Around a year after that,the car over heated again. I had it towed to a auto repair shop that I worked at and had them test the car to see the problem. It was a blown head gasket again. They determined this by testing for any emissions in the coolant. There was also a large amount of sludge build up in the coolant reservoir(oil)as well. Subaru would not warranty there original work so the car sat for a bit before I could afford to have it fixed. When I saved up some money for the repair, I brought it to the Subaru dealer to have them do the work on it. I was extremely upset with the work they did but got the car back with a functional engine. Not more than a year and a half later, the same thing happen(overheat). Again, I pulled over right away to limit any further damage to the engine. At that point, I had the car towed to my home and it sat for about a year before the bad choice to repair it again. This time I sent it to boffo auto repair. They recommended a new motor because the last time the "heads" had been done, they milled the heads smooth and new "heads" were not to far of the price of a used engine. Boffo finally found a used engine for my car that apparently is very difficult to find. The engine had 32k on it and was reported to have been checked over as a safe,reliable motor. After spending over $4000 this time around, I had a working car again. The car came back to me not even 3 months ago. The engine over heated "again" the other day and again I have a head gasket leak(oil into the coolant). I have been looking on the internet about this problem and it seems to be a big one on the 98 vehicle. I found out that they only made that motor for the model year 98 only. Why is this? I have been informed by a Subaru employee because of the head gasket problem. I need your help. I have contacted an attorney this morning and will have him get in touch with Subaru.