The flex plate (flywheel) will go on several positions, but, because it has the sensor wheel attatched, it can only work in one position. If you did not mark the original position before you took it off, more than likely it was installed incorrectly. I learned this the hard way. I am not sure which repair manual will give you the correct position, but be sure when you set the engine at top-dead-center, the timing marks on the cam gear also line up. The one I messed-up on also had a crankshaft pulley that the timing mark had slipped that took me two days, a timing belt, and alot of curse words to figure out.
Good Luck
Rick