Ford Repair: 1995 Ford Escort, spark plug wires, hairline crack

Question
Hi: My son recently purchased a 95 Ford Escort that appears to be in very good condition except for a few (Minor?) things. When on the highway and accelerating past 40 mph the car shakes or shudders. When he lets up on the gas pedal the "shudder" stops. Any help or suggestions will be sincerely appreciated. Thanks!

Answer
If the "shake or shudder" only happens on acceleration, and not when coasting or deceleration, I would guess that engine is misfiring.  I would start by checking the spark plug wires.  You can use a spray bottle filled with water and spray the wires down while the engine is running at idle.  Look and listen for the spark from the wire arcing to ground.  The spark plugs could also be worn or have a cracks in the porcelain.  Black lines (carbon tracks) on the white part of the spark plug indicates a hairline crack.  If the wires and plugs are okay, it could be a bad coil.

I hope this helps,
Dave