Slant 6 power issues

It sounds like you got the distributor back in a tooth off. Remove #1 plug. Disable the ignition. Have someone bump the engine until you can feel compression push your finger out of the #1 hole. Look at the balancer and find the hash mark on the balancer. Now, turn the engine by hand clockwise and bring the hash mark up until it aligns with zero on the timing mark. Finally, remove the distributor cap and see WHERE the rotor is pointing. It should be at about the 5 o'clock position, pointing toward #1. If not, remove the distributor and install it correctly. In case you get the wires off, firing order is 1, 5, 3, 6, 2, 4 going clockwise, starting with #1 in about the 5 o'clock position.