Saturn Repair: 1997 Saturn SL2, valve replacements, saturn sl2

Question
I own a 1997 Saturn SL2 5-speed approaching 150,000 miles.  I've maintained the car very well since buying it new 10 years ago, but over the last year and half, my SES light comes on about every 6 months.  The dealership has explained that carbon build-up is the cause and usually recommends a BG fuel system flush accompanied by either an EGR or PCV valve replacement, and sometimes an oxygen sensor replacement.  Problem is, these services end up costing $300 to $500.  Is there a less expensive alternative to these fuel system flushes and valve replacements?  Would more frequent spark plug changes help?  If so, how often (mileage-wise)?  Any brand of spark plug that is best?

Thanks.  

Answer
Hi Jim

Which dealership? Also I haven't done a fuel system flush but I have done a 30k  and 80k  what that is , is a maintenence that could include , fuel injector cleaner put into your gas tank, a 3 stage, which hooks up to the engine and runs cleaner through your engine and gets rid of carbon and a throttle body cleaning. along with new plugs and fuel filter.........thats the best you can do for the car, a little pricey, but you'll have your new old car back running great

ERIC