F
Flungo
Guest
I drove my 2003 Buick Park Avenue Ultra from Ohio to California. I have had the car for 2 years and have only filled it with regular gas. I have never had any engine related trouble with it. I have been in California for a month and the car is running poorly. The first time I took it to the mechanic, the car was rattling on acceleration and the 'Service Engine Soon' light was flashing on and off. The mechanic told me to use premium fuel instead. The rattling went away, but the car now idles very rough. Every 5-10 seconds the RPM drops and it sounds like it is misfiring. The 'Service Engine Soon' light came back on and stayed on. The mechanic said it was an old code that said misfiring cylinder and told me again to continue premium fuel. It is now my fourth tank of California premium and the car still idles rough, and the 'Service Engine Soon' light is still on. What do I do?