The 2.3L I4 is not a silky smooth engine. The version that goes into the Rangers and B2300s is missing the balance shafts that would otherwise cancel out the vibration. I was not happy with it when I got my 2004 Ranger but it doesn't bother me now that I know it is 'normal'. I only notice it now when I'm stopped at a lite etc. and it's not bad enough to cause any rattles in the exhaust system. Maybe you need to sit in someone else's 2.3L to get a better comparison of what's a normal amount of vibration.