All suggestions sound excellent and as best I remember none of them have been done. I am especially interested in the difference in spark plug problem that was mentioned. But I am concerned because the original spark plugs that were in the car have been discarded - so it will be impossible to know exactly what came out. Any suggestions to be sure I get the ones I need if I can't compare to what was there before?
Once again, thanks to all of you experts! Maybe if I sound like I know something my mechanic will do a better job!