Well here goes. I replaced the harmonic balancer a few weeks ago and I noticed recently that the pulley was either bent ot misaligned. When I took the balancer off I noticed that the two metal sheilds that run in the crank shaft positioning sensor where,what looked like to me, out of line. I checked them against the old one and sure as heck they were. Well now that I have the new harmonic balancer in the car the "Sputtering" has stopped and the mileage has increased to 23.6 mpg on the highway. Oh I also replaced the crank sensor too.