I don't know how picky you are about your plugs but I just tried the bosch platnium 4's and the seem to run a lot nicer the the 2 prongs. Even idles about 100 rpms lower. If your getting that bad of milage you might want to check the air filter in the process. I just got my 4th gen 2 weeks ago and haven't tried any of the other stuff for tune ups other than a new distributor and cap. I don't know about the timing since I had a shop do it, but I don't think you should. I've had pretty good luck with accel and a few other performace brands in the past. I don't really care for using NGK or Denso.