95 w'star tune up

was just wondering what the best approach was to changing the spark plugs on a 95 with a 3.8l the ones on the right bank look tough. i have shudder when driving this vehicle and i thought at first it was a tranny problem but it is now starting to appear that the engine is intermittently skipping. this van did belong to my inlaws and they said they had new plugs and wires put on about 10k miles ago, i have inspected the coil pack and i don't see anything out of the ordinary, anyone got any ideas???