Its not the parts price that will get you... its the labour of course. This is a tough call I guess. One thing is, you know the car. All things concidered, you know its strong points and its weak points. Its concerning the car has had so many injector problems though.
Personally, I like any GM with a 3300 engine or a 3.8 or 3800 series (which is the next update of the 3.8). I'd say dump it. My Cutlass Ciera 1991 isn't a luxury car by any means, but it passed emmisions today with flying colors with the OD at 280,000 kms, has great oil pressure, and gets combined average of 21 MPG (reviewed new as getting 23 MPG).
I never liked the Cutlass Supremes from that year. they have the OBD 2 and a lot of electronics that arent that reliable.
Good cheap cars that last with proper care:
1. Olds Ciera 1990-1993
2. Buick Century same years
3. Chevy Celebrity
4. Buick Regal
5. Buick Park Avenue
Try for cars with either 3300, 3.8, or the 2.8 from the early 90's.
Just my .02 cents