inch and a half up on the seatpost? That will alter your pedalling/backside position tremendously. It shows that the previous stem was too short, and yes the bike is going to feel wierd. CofG is now higher, and I wouldn't mind betting that you are further away from the bars aswell.

I'd give it a try for a few rides to see how you are getting on with the "new" feel to the bike. If it still feels awkward, then stem spacers may help a bit but you may need a higher rise stem if there's no room for them.