Random misfire on cylinders 1,3,AND5 WHAT CAN CAUSE IT on 1998 Cadillac Catera

after about 5 OR 10 MINS IT READS CODES 300,301,303,305 AND IT IDLES ROUGH

Asked by for the 1998 Cadillac Catera
2 answers 2 comments
could also be timming belt
These cars typically burn up the coils and ignition module, we have done several in the shop where I work. The valve covers leak oil and then these ignition components get oil soaked and fail.
This is a pricey repair, like $1800-2000, with the valve cover work, which must be done. The engine in your Caddy is a SAAB motor which is VERY high maintenance.
I was not aware that Caddys and Saabs share the same engine. Although, I do know that 3.0L Saab V-6 is a GM engine that Saab did minor adjustments to(at least that's what they told us at Saab FTP). Saab used a slightly thicker head gasket to lower the compression, added a turbo, altered the intake and exhaust manifolds, and added Direct Ignition with a "Trionic" ECU.
actually the Cadillac catera is an opal product not a saab, it is a rebadged opal omega.