You probably have it timed wrong. If you went by the Haynes manual, some of them are wrong on the procedure.
What you need to verify/do....
Remove the timing belt cover and rotate the engine by hand going clockwise (removing the spark plugs will make it easier to turn the engine over by using a socket on the large crank pulley bolt), until piston #1 (the one nearest the radiator) is at TDC on the compression stroke (the "dot" on the lower timing belt pulley/cog will be at the 12:00 position (there is a "pointer" right above the cog that you align the dot with).
Verify the mark on the cam pulley is at 6:00 (both sets of rocker arms on the #1 valves should be loose, if you happen to have the valve cover off, so you can check them). If the #1 valves are not loose (that means that the cam pulley mark is probably at 12:00, instead of 6:00, or that you are off a tooth or two with the timing belt), rotate the crank pulley one complete revolution and recheck the cam pulley mark and/or #1 valves).
Once you are sure that the timing belt is not off a tooth or more, you can pop the distributor cap off and make sure the rotor is pointing right at where the #1 tower is (the tower that the #1 spark plug wire is attached to). If the rotor is not pointing at #1, the remove the distributor bolt, pull the distributor and reinstall it, so that it aligns with it, when the distributor is fully seated and moved to about the center of its adjustment range.
Once you have that verified, make sure the spark plug wires are on in the right order. The distributor spins clockwise and the firing order is 1-3-4-2.
Some people prefer to set up/check stuff with #4 at TDC, instead of #1 (since there is actually a mark on the top of that plate that sits behind the cam pulley, to align the cam pulley mark up with). If you want to do it via #4, just make sure the cam mark is at 12:00 (instead of 6:00) and make sure #4 valves are loose and that the rotor points to the #4 tower, instead of #1.
