Ford Repair: ford crown LX 1998, champion spark plugs, spark plug wire

Question
My car has started this recently. It starts up running smoothly and if you drive and apply gas very slowly it continues to run fairly smooth but if you get under a little strain it starts to sound as though it wants to skip and jerk then when you get up to speed it smoothes out until you put it into a strain like going up a hill. This car had a tune up less than 3000 miles ago, does not use any oil and has been carefully maintained since it was new. Got any possible ideas as to what it is?
Thanks for your time and have a great day. Charles

Answer
have you had the spark plug wire and plugs changed ?? very common concern. problem is, the local garage installs autolite/champion spark plugs because they are cheaper- this engine     is very sensitive if you don't use motorcraft plugs and wires,, plug gap/ resisatnce in aftermarket parts vary greatly.