1995 Ford Escort Spark Plug Removal and Miss under load

Hello, my daughter just picked up a high mileage Escort with a 1.9 4 cylinder engine. Drove it home over 150 miles and it ran great unless you lug the engine then there is a miss present. I figured to replace the plugs and wires as they both look pretty old. Problem is the plugs seem to be pretty tight. I can break them loose but they turn awfully hard and I don't want to strip one out. Is that normal them to be that tight coming out? Also, am I on the right track with the plugs and wires? Any info appreciated.