94 Ford Escort GT surging?

I recently replaced the distributor, spark plugs, and spark plug wires including the coil wire on my father's 94 GT and he says that it hesitates and surges and that he noticed a considerable loss of power. I'm really not sure where to go from here. I checked all the spark plugs before I changed them and made sure that they were gapped properly and I made sure all of the plug wires were properly secured. What should I check? What direction should I look in?