Madmarti

I am having a problem with my 97 SC2 (110k miles). About 2 months ago my car was acting funny. When I started it up I noticed a jittery rough idle and then when I accelerated it was still rough. When I got above 35/40 my service engine soon light started flashing. I took it t the dealer and they said the number 3 injector was bad and it needed new plugs and wires. I had them replace the injector and I did the plugs and wires. This morning it had a rough idle again and again the SES light started flashing after reaching 35/40, but not as bad as the first time. when I got above 60 it started running normal and the light stopped flashing but remained steady. Any ideas? Are my injectors just dirty?

FYI: My car also has started to wear its o-rings and burns oil. I decided I would live with just adding oil. I switched to a heavier grade oil (10W40) wich but did not elivate complete oil burning.

Thanks for any advice.